Hi, Solomio. I'm sorry for the death of your MIL. My MIL passed away years ago, but I still miss her.
In the last few years before I left my STBXAH, I had to take his name of my bank accounts and debit card because he'd deposit maybe $100 - $200 every couple weeks and still pull out $100-$500 a couple times a week. (No that math doesn't work.) On the rare occasion that I had a little cash, he'd steal it out of my purse and blame it on our young son who was 1 or 2 at the time. I had to make sure that the bills were paid or figure how to pay the past due amounts and fees after I believed him when he promised to pay a certain bill for the month. I ended up begging him for part of his paychecks so we could pay the bills, but told him he could keep the rest to spend on gas, steak, pizza, whatever he wanted (it usually ended up being vodka). It was not fun.
I was the only person who could decide when it was time to leave. When I made the decision it was based on what was best for me and my son. In order to move forward, I had to make a very conscious decision to try to not give too much weight to my STBXAH's 'needs', or I would probably never have left him. There was always something that he was dealing with: He was still depressed about his mother's passing. He was still depressed that he had to close his business and he (even though it was WE) had to declare bankruptcy, and he had to start working for some one else. His employer - a large international company - was 'still messing up [his] paychecks' or they didn't pay him again that week (Yeah, right.) He was getting cr-- from his supervisor(s) about him doing work he wasn't supposed to do. (Huh?) Then he told me he had cancer - which turned out to be lie, but....
I guess my point is that there was always some 'reason' that I shouldn't leave or shouldn't have left him to take care of himself. I had to decide what was best for me and my son. I also had to figure out what guilt I could deal with. (I swear that the guilt for staying gone from my husband as he dealt with cancer nearly ate me alive, but there were other factors in our relationship that outweighed even that.)
Best wishes and hugs.