My mother was emotionally negligent in raising my brother and I as children. Now in her mid 80s she wants this close relationship. Any advice?

She is living in a facility that has staff that are paid to care for her.
If you feel you must visit out of some perceived obligation then visit 1 time a month, 2 times a month or 1 time a week. Whatever YOU feel YOU can do. Set a timer on your phone for your 10-15 minute visit. Then leave.
On the other hand if visiting is not emotionally healthy for you then do not visit at all.
Emotional health and safety is just as important as physical health and safety. If your mother had beaten you and left you with visible scars, bruises and broken bones no one would question the reason you do not want to visit. Just because a wound is not visible does not mean it is less important or less of a wound.
Do what you feel is right for you.

The description of your mother is basically exactly both of my parents. You are correct. She tries to be all over you because you're the only person who visits her. Everything you say is true because you're the one who lived it.
So now it's for you to decide what the relationship will be with her, if in fact you even want to have one. It's okay if you don't.
Keep in mind that everything you do for her and every time you visit her it's an act of pure kindness and generosity on your part.
You have to forgive yourself and get past the guilt that controls you. You don't deserve that. Try therapy to help get past the guilt you have.
I knew many a bored and lonely elder who complained that their kids don't bother with them and don't care. Usually I knew the other side of the story from their adult kids. You know what I always told these people?

If you plant a field of resentment and indifference, don't expect a crop of love and understanding when it's harvest time.

Know what I always told the adult children these elderly people?

Everything you do for your undeserving parent is a gift of kindness and generosity to yourself.

This doesn't mean you have to visit her every day. You decide how much contact you have. This doesn't mean you have to become a slave to her needsor tolerate abuse from her. When she starts up with the passive/aggressive behavior and paranoid nonsense start up, cut her off. Hang up if you're on the phone with her. End the visit if it's in person.
You set the tone of the visit. If physical contact with her makes you uncomfortable, don't allow it. If you don't want to hear her complaining crap, refuse to listen.

Your mother has Alzheimer's Disease, according to your profile and the category you put your post under, plus she lives in Assisted Living. Her brain is broken and that's why (possibly) she's looking for physical touch/affection from you NOW which she never looked for from you in the past. Things change when dementia sets in. I was adopted at 3 months old, and when my adoptive mother's dementia became moderate, she started carrying on and ON about how sad she was she never had 'children of her own' and how it was 'dad's fault' and blah blah. It became an exercise in patience and tolerance for me to visit with her at all, and be this tower of strength for HER while she was cutting ME down. It became awful to deal with her, even MORE awful that it had been in the past to deal with her histrionics and dramatics.

So, what your mother 'wants' and what she will 'get' from you are likely two different things. Give what you are able to give and not what you are unable to give. Visit when you can, stay until things become intolerable, and then leave. Me, I never visited mom alone b/c one time she told me something SO foul, that I decided it was not wise to visit her alone anymore. So I'd take my DH with me as a buffer. If she became too toxic, I could leave the room and have DH take over 'entertaining' her b/c she'd never act up TOO badly with him. This is why the buffer idea was a good one.

Do what you can and not what you can't. Deal with mother on YOUR terms now, you're no longer a child living in HER home, but an adult visiting her.

You're entitled to your feelings; feelings have no consequence unless they're acted upon. You've earned the right to dislike your mother and/or her behaviors, as I earned the right to dislike my mother and her behaviors. Before I acted out on MY feelings, however, I'd leave her presence. So I never had anything to feel 'guilty' about with respect to my OWN behavior. I'd stay as long as I could bear to, and then take off. I suggest you do the same. Don't dole out physical affection b/c it's unnatural and not warranted ANYWAY. A small hug or air kiss on your way out should suffice in terms of 'affection.' You get what you get from me, mom, just as I got what I got from YOU growing up.

Wishing you the best of luck carving out a relationship with your mother that works for YOU and that's all done on YOUR terms now.

I've said this story before, and I post it again here.

My dad came from an abusive household. No physical affection, lots of verbal abuse, maybe physical, too -- he never got into details.

He grew up to be a kind and loving family man and a pillar of his community. No one in the community knew about his ppbringing, nor did my brother and I until about 10 years ago.

After hearing some of my dad's stories of his upbringing I asked him how in the world he became the wonderful person he was, and he said,

"Whenever I didn't know how to handle something, I'd ask myself what my parents would have done. Then I do the opposite."

That, in my opinion is how you get past trauma. My dad was not a repressed personality, but he chose not to dwell on the negatives and he made a conscious effort not to let those experiences form who he'd become unless he could learn from them by doing the opposite. He knew that by hanging on to the memories and bitterness, the actions of his parents would last long after they were gone. He cared for my grandmother in her old age because in spite of her failings as a mother, she tried.

Think about that as you make your choices.

Lived this. My mother was a severely damaged woman, riddled with anxieties.

I was her only child, and during my entire early life, in fact until I was married in my early 30s, she was a tragic agoraphobic, and never saw any of my graduations or recitals or performances because of her illness.

In her last years, we BOTH learned how to come together for each other.

I was open to acknowledging that she had been a wonderful amazing grandmother, and she learned to acknowledge in her own damaged ways that she loved me sincerely as her daughter.

Her dementia actually allowed me to overlook and release a lot of what had been her earlier years, and we both benefited for the changes I made.

In a sense, you are fully in control of how “close” you want your relationship to be. See if it helps if you can frame your interactions as being with a damaged stranger, who no longer has the capacity to herself willfully damage you or your brother.

After all the years of flawed interactions with my mother, our last years were pretty much smoother. I treasure that time. Living through all of the steps helped me to grow as a human being.

I hope you’ll be able to let your mother give you that gift, as my damaged mother did for me.

I understand what you are feeling. My parents raised me but my father always treated others as if they were more important than I was. Their opinions and feelings mattered more than mine did. If someone hurt my feelings I wasn't to say anything to upset the offending party. Even as an adult he would make plans with me then cancel out if something better came along. Knew more(took more of an interest in) about the lives of the workers at the bank he went to than his own grandchildren. Then he got really old and the friends and family he held in such high regard dropped off. Suddenly I was the most important person in the world to him. For me he was 45 years too late and I just could not get past that. The idea of hugging him made me ill. I just did not have that connection with him. I am sure he was confused by all of this. I understand how you feel.

I’m sorry you didn’t get the mother you needed and deserved. That will leave a hole that can’t be filled as you’ve seen. Know that you can’t get back at her now for the bad choices she made in parenting. She won’t understand, ever, what she did wrong. Now, she’s an elderly lady whose mind is leaving her, and still difficult to be around. Everyone in any managed care setting needs someone overseeing their care, being their advocate, making sure the staff is doing well by them and seeing that this is a person who is cared about. That doesn’t mean you have to spend loads of time. Separate yourself emotionally and views the visits as checking in on a person in need, just a person. It won’t be easy, but with that mindset it can get easier. When the rudeness starts, leave immediately. And though it’s highly unlikely that “someone more interesting” will come along, if they do, let them have at it.

Burnt--
What a great saying about, well, basically, reaping what you've sown!

I was not close to my mother. I tried, as best as a kid can and even as a child knew, somehow, she was not capable of truly loving without expecting anything in return.

I've always felt that if you have one person in your life who loves you unconditionally, you are lucky. If you have 2, you're beyond blessed.

My dad and his mom were my 2. And it was enough to get me through to adulthood where I choose to love and am loved in return.

Don't play 'tit for tat'--be kind, considerate and compassionate as your soul allows you. The person who suffers is the one who didn't/couldn't love you.

(Lest you think I'm a really great person, I have to add that I have zero relationship with my MIL. I truly tried and beyond--but being with her was so depressing and negative, I was counseled to cut all ties with her. We don't have ANY kind of relationship, good or bad. Just...nothing. And sometimes that has to be OK, too.)

My mother was emotionally unavailable too. Not affectionate with me my entire childhood. She made me feel like a burden. Sometime in my mid 20’s she started wanting hugs and because of the history it made me very uncomfortable. I still don’t like it and really won’t do it. I think parents have a chance to bond with their kids when they are young and if they don’t do it that is on them. You shouldn’t feel bad at all.

My mother, she was and is a terrible mother, it is all about her and what she wants. She is a verbal abuser and was a physical one when I was a child. Her interests when my brother & I were young, was Boys, Bowling and Booze, not her children.

When my brother was still a baby she would leave us alone all night, I was 11 when he was born, she was out partying.

I went no contact with her 11 years ago, I had to choose me or her, I chose me.'

Happiest 11 years of my adult life, to me she is dead.