What to do when your spouse will not help you take care of his elderly parent?

I think you should resign the caregiving role. You and husband both work. No reason all the tasks should fall on you. FIL has other relatives. No reason all the tasks should fall on you. So why are you allowing that?

The first thing I'd resign from is arranging all family holidays around FIL's wants. Take them into consideration, yes, as you would for any family member. But either 1) you get to plan the holiday as you see fit or 2) your husband or some other family member can plan and prepare the celebration. You having the responsibility but not the authority is simply not reasonable.

One by one, resign full responsibility for other tasks. Shopping? Decide whether you are willing to do some of it or none of it. Announce that decision and stick to it.

Doctor appointments? You will do 2 per months. (Or 1 or 0. You decide.)

You could resign in a big bang, all at once, or piece by piece. What would work better in your household? You can resign fully or continue to make a contribution. But extricating yourself from this unfair situation is the only solution I can see.

Hey Blueprint
If you are going to take the three weeks off, do it DURING the holidays.
No seriously.
I know you will need to put your big girls on but there is no one who can make this change but YOU.
If someone was going to step up they would have by now.
What's your vision?
Does help of any sort sound good?
Do you need help with bathing and meds?
Do you need someone to cook?
I know you need a house cleaner.
Would a plumber be the place to start?
You don't know how much power you have. Your family would fall apart without you. Don't take that to mean that you have to keep doing it. Take it to mean you can stop doing it all. You need to stop doing it all. Catch your breath. Get a plan.
Maybe a therapist would be the place to start?
Does anyone have POA for health or finances?
Make a list of all that needs doing.
I am the POA for an aunt who is actually my husbands aunt. No relation. But she is my friend. So I do what I do because I want to. When I started to burn out I started adding layers of help. I started with HH. They do the meds, the baths, the vitals. Another pair of eyes to keep things real. They call in physical therapy which is a huge help.
Then I added a housekeeper. At first just once a quarter. I have a yard man. Her little poodle gets picked up for grooming every six weeks. I got her meals on wheels. Then I added a daily aid to give the meds. Next I hired a couple (relatives) to buy groceries, make her food, pay the aids, manage the cameras I added after a fall. Run over when she presses her medialert by mistake. Someone to understand all that needs to be done for her besides me.
She's up to a daily aid three hours a day now.
All of this is paid for by her.
I still manage it all and handle her finances and take her to her doctors appointments.
Frankly I can't imagine doing it all anymore. It helped so much each time I hired a layer of help. I will continue to do what's necessary if it costs her all she has because that's what it is for. When she runs out, if she does, off to the NH.
Your FIL obviously has assets that mean nothing to his heir. Use those for his care. If you don't know how come back and let us know what you need help with. But only you know where you are right now today.
What are you afraid of? Stop in your tracks and get help.
And we haven't even talked about your FIL. What does he want? Your husband nor his family should enter your mind as to what they want because they are not honoring him or you. 

Hmmm ... sounds a little familiar. When my in-laws moved here two years ago for "us" to take care of them, everyone knew it would be "me" doing most of the work. It's just how it is for us. My husband works, sometimes long hours. I'm a SAHM who had six kids at home, and I homeschooled. (One has since graduated and is off to college. The youngest two have now entered a traditional school because I just can't do it all.) People will treat you exactly how you let them treat you. I allowed his mother to yell at me one last time, and then I quit. I still do all the behind the scenes stuff -- pay bills, make appts, manage meds, etc. But I've hired helpers for anything that requires being with her for more than a few minutes (driving, errands, cleaning, etc). I simply do not have the time nor the inclination to deal with her drama. My husband takes her to dr appts. Who set all of that up? I DID. *I* did it, because *I* needed it. I didn't act arbitrarily. I talked it thru at every step with my husband. These are his parents, so he gets final say. But he loves me dearly and hears me when I speak. After 27 years together, he knows I'm tough and can handle a lot, so when I say I'm done, he believes that! Sounds like from your post that this has been the status quo for quite some time. But now you're ready for a change, and that's ok! However, no one will recognize this unless you TELL them. It doesn't have to be a dramatic screaming fit. A quiet, "I'm done, babe. I need help." can be just as effective. Decide what you need help with and get that help! ---- P.S. A week on a sequestered jury can help open his eyes to all you do! True story! LOL!!!

Who is the POA and Healthcare POA? Since, it's obvious that your husband isn't interested in helping with the caretaking, I'd explore hiring a professional to do it. Why would your husband want to jump in when you are doing it? IT's a lot of hard work. It's generally not possible to force people to do things that they don't want to do. Some people just aren't inclined to take it on. Apparently, it doesn't bother him that you are overextended. That has to hurt. Is this insensitive in other areas? I might evaluate this.

Can your FIL afford to hire helpers or even a Senior Care Manager?

I work also. During the time I was taking care of his mother who had Alz. , I was also helping my sister take care of my own mother who had Alz. My husband has nieces that refuse to even help me clean their grandfathers home which one of will get when he passes. His house needs the bathroom redone (he has the money for it to be fix) , but my husband will not fix it and he knows how to do all the work that needs to be done. Example: His dad fall and I was shopping and he calls to come home and dress the wound because he doesn't know where the first aid kit is! My first question was : Did you check your dad to see if he broke anything and then did he pass out? His answer was he is just bleeding on his arm a little! His dad takes blood thinners and has had strokes in the past. I just feel like after taking care of my mother and his mother without any help from him or his family that I'm at the end of the rope now that I am having to the one to take care of his dad.

I’m going to guess that having polite conversation on all this is a waste of time....

If so, then I’d suggest you roll up the doormat and schedule a 2 - 3 week trip away.... visit a cousin, friends, your own family. Volunteer for a 2 -3 week rebuild program through a church group for this summers hurricane hit zones if need be. Leave & make hubs deal with it.

Really once he’s on Day 3 of butt duty, things will change. Don’t return ahead of schedule. 

While I don't know all of the facts here - it sounds like your husband needs a good smack on the head to knock some sense into him! Gee whiz - If he is unwilling to help take care of his own father, the man has a serious character flaw.

It's time you sat down with him and laid things out. Develop a list of "reasonable" things that he can be assisting with. Even if you are full-time housewife, your husband has no right to expect that you do everything to care for his father.

Your husband needs to learn how to do all of these things to assist his father. What if something happens to you - and you are no longer able to provide that care? He needs to be taught what to do and how to do it.

You don't mention anything about how you got roped into this role to begin with, or what your (and your husband's) other responsibilities are. If you are a stay-at-home wife and your husband supports all of you, it makes sense for him to think that you are the logical person to take care of his father's needs. I'm not saying that's necessarily fair or that it can't be abused, I'm just saying a fuller picture is needed before giving any advice.

Understandably, you resent being stuck as a caregiver to your inlaws without any help or appreciation. But what are the choices here? Do your husband or his siblings have free time to ferry your FIL around or help with his needs? Can your FIL or the family afford paid help?

If you share a bit more about your situation, we might be able to help you better.

My instinct is to say dump him! It's his father!!! Why on earth does he expect you to do all the work?

However, this one thing my mother did when my brother and I were little changed my father's worldview. It might work for you. She up and went to stay with her sister for three weeks, and left him in charge of us and the house. When she returned, he was very humbled about the amount of unpaid work she did in the home, and started to take quite a different role after that. (This was around 1974 and they divorced three years later anyway. Your mileage may vary.)