Glad to hear you and your DH have a decent plan. I have to say that we had a similar situation and it nearly caused our divorce. My DH was unwilling to set boundaries with his father and, of course, his father preferred DH to anyone else when it came to care giving. In our case, his father became permanently disabled so it is different than your but we didn't know that going into it. We had significant relationship counseling but, unlike in previous rough patches, it did no good. I even started individual counseling. It was really a tough time and if I had to do it over again, we should have gone to our relationship counselor first to establish ground rules. As a PP said, going into it with no plan is a recipe for disaster. It's too late when you're in the midst of it. I resented my DH and my FIL for a very, very long time. In all honesty, even though my DH is more to blame, I still have a lot of anger and resentment towards my FIL and it totally changed our relationship - which used to be positive.

What is the kids' day care situation? DH needs to know you will not take any time off work. With 2 kids and a spouse with no leave, you will be the point person to take off when they are sick and you'll need to have leave available for that. Perhaps you need a schedule that you each help her after work on alternating days. He needs to be committed to pulling a fair share with the kids, housework, yardwork, etc. as well.

And above all, everyone needs to relax standards for a while. Meals and chores may not be up to the usual par and everyone is just going to have to deal!

I assume he has no other siblings?