Guilt never sleeps. Any advice?

Your mom has issues. You are VERY lucky that your sister took her in. Mom would likely not be happy anywhere in any situation, etc.

So, look honestly at what you DID do for her. Wow - it's a LOT and waaaaay more than most of us would have even considered doing. You're an over achiever. Give yourself credit!!

That last thing to check on is how does your sister think mom is doing? Do you trust your sister? I assume so, so back off a bit. You do NOT need to take every call your mom makes to you. I'm assuming they are excessive - don't answer if they are. Set a limit of how many calls you will take (one a day?) and stick to it.

If she's bad enough to have sundowners, how is she even making all these phone calls? My mom doesn't have that yet but can rarely make calls. But everyone's dementia is different.

Be kind to yourself

OMG you’re a wonderful daughter and you’ve paid the bills and you’ve listened to mom and you’re beating yourself up minute by minute and you’re not going to stop until you’ve expiated yourself from all your sins and then - um, well, then WHAT? Then you bring out the leather whips and lash your back until you bleed and THEN WHAT? Then you still haven’t piled on all the guilt you deserve and THEN WHAT? Please stop hurting yourself. You have done everything you could possibly do. You do not need to pile on any more punishment because you deserve a life free of guilt (that you never deserved in the first place). The problem is in the way you think. Change that and you’ll feel better. So that’s your job - change you and give yourself back to your own life. Give your mom back to hers. It’s going to take a while but you deserve better. You are a person of worth and accomplishment and you can do it!

As Grandma1954 said, your mom would be calling you from wherever she is living, likely with the same complaints and threats. As you said, her doctor determined your mom should not live on her own. You were the one person who knew all this and were put in the position of doing nothing different, or making the hard (aka best) decision with the information you had. I applaud you for making the hard decision that your mother could not make herself. Now it's time to let that give you peace as you now live your life. Kudos!

Well, my mother was always a drama queen & threatened suicide since I was a small child, to the point where she'd take off in the car saying she was going to 'drive it off the bridge' to her death. She never did, of course, but what she DID manage was to turn me into a nervous wreck as a child. Which trickled into adulthood and made me promise I'd NEVER take mom into my home or take on the burden of doing the hands-on caregiving for her in her old age. Dealing with her histrionics was too much as a child, and when it turned into dementia in her old age, was WAY too much to deal with for me, so she (and dad) lived in Assisted Living. Then after dad died, mom segued into the Memory Care building of the same AL where she lived for nearly 3 years before she passed at 95 years old in February. Threatening to 'kill herself' at least 2x a week ever since. She died of advanced dementia & heart failure, not suicide.

No matter what I did for her it 'wasn't enough', to hear her tell it. To hear me tell it, it was plenty. More than enough, in fact, and I took on NONE of her financial bills or issues; she paid her own way through AL and Memory Care AL. I don't harbor any guilt at all b/c I did nothing to cause her problems, could do nothing to cure her problems, and there was nothing I could do to control her problems or her disease EITHER. Old age & infirmity were my mother's issues in life, and I was there to try & help her manage them, that's all. To think I was capable of doing more for her than that was to think I was God, and I know that I'm not. And unless YOU yourself think you're God, what more are you capable of doing than to help your mother feel safe and to support her? You've already done too much as it is, by financing her life and paying off her bills, to your own detriment. And STILL you feel like you haven't 'done enough'. What would it take, exactly, TO make you feel as though you've done enough for her? Answer that question, and I will tell you if you were to meet that goal, it STILL won't feel like enough b/c your mother will still have dementia and based on your math, you'll still be 'the bad daughter' as a result.

It's your thinking that has to change in order for you to find peace. You have to realize that your mother's disease is hers and not yours. Her age & infirmity is something that goes with HER life and not yours. You can't fix 88 with dementia, yet you still insist on trying. Your mother won't be happy no matter WHERE she goes b/c she has dementia and that's what's making her sad & upset. I used to say that I could put my mother up at the Palace of Versailles and she'd complain the gold was tarnished. I could jump through every fiery hoop on earth and STILL she'd be sad & miserable b/c that's who she WAS. Not my fault.

The only time I felt any relief from all the burdens of my mother's life was when she passed away in February. She foisted her ills upon me in spite of the fact there was nothing I could do to 'fix' them. I was her shoulder to cry on, her post to scratch on, and her sounding board to vent to. Me & only me. It's a huge burden to bear, but once I realized I couldn't fix her, it became easier. But there was no relief until she passed, to be honest. That's not to say I don't miss her, I do, just that the burden wasn't lifted until that time.

Wishing you the best of luck coming to YOUR realization that none of mom's problems are your responsibility or your fault.

Ignore the suicide threats. It’s just a means of manipulating. Like when a small child threatens to run away from home if you make them eat their veggies,

You have done and are doing your best. Don’t forget that. I feel a lot of guilt too, and I can relate in a similar way to your story. However I have to step away for a while, I’m not sure for how long, as I am fighting for a liveable life. Im stepping away from the guilt, the obligation, and the desire to be a good daughter. As one of the articles here said “ don’t just stay on a runaway train once you get to the point of overwhelm, you will ruin your health and destroy your relationships”. At some point you have to say “I can’t do that right now”. You will know in your heart you have tried so hard to be the best daughter. You deserve to not feel bad about what you’ve done for your mother. Have a break, set some boundaries and keep to them. Sending hugs to you.

Mom has dementia.
You can take what she says with a grain of salt.
If she called you and said your sister was beating her, starving her would you believe her? If she called and said someone kept stealing her things would you believe her? If she called and said someone was talking to her all night would you believe her?
What does your sister say?
This is the one that has "boots on the ground" and knows what's going on with mom.
According to your sister is mom adjusted well? Is she doing well? Are there any problems that she can not handle?
Your mom would probably make that same phone call no matter where she was living.
bottom line is ...
Is mom safe where she is? If so that is all that matters.
big question is How is your sister doing?