I was in a similar situation a couple of years ago. My MIL moved to our town about 8 years ago. We provide a lot of financial assistance to my MIL...we put a roof over her head. About 2-3 years ago, MIL's demands on our time were getting to be just insane. Every time my DH & I would go out on a date night, within a week of that, DH would take MIL out on a date night and he would pay for the whole thing. Then she would want time alone with DH for hours at a time. Then she would call at crazy hours of the day demanding that he go over to her place RIGHT NOW to fix something that was 'broken.' Not really broken....usually a computer thing that she couldn't figure out. But he would drop whatever he was doing at home or with us and run to Mommy's aid.
My MIL, like your BIL, is a drama queen. Twists everything to be all about her. Oh, you're going on a vacation? Then she would make passive-aggressive comments like your BIL does about "Gee, must be nice. Nobody ever asks ME to do stuff like that." This wasn't just once in awhile. It would happen every time we saw her or spoke with her on the phone. She even started demanding that we give her money for gas for the times that she would pick one of our kids up from daycare early that day because the little one was sick or something.
Eventually, I'd had enough. My DH at the time didn't have enough of a backbone to reinforce proper boundaries with her. So I gave him an ultimatum. It's me or her. I flat out told him that he could only be married to ONE person...me or his mother. If he insisted on running over to her every single day and taking her on dates every week and giving her gas money, etc., etc., then he could move out of our house and move in with her and I would find a lawyer and file for divorce.
A few things happened after that over the course of 4-5 months:
- DH's first gut reaction was "NO THANKS! Why would I want to live with my mother? She's IMPOSSIBLE!"
- DH tried to push the envelope MANY TIMES over 4-5 months. He pressured me A LOT to just cave and do X or say X with my MIL in order to play "Happy Families." And whatever "X" was...it was usually something that involved me sacrificing my own boundaries or principles for the sake of MIL getting her way and MIL getting away with treating us like garbage.
- DH and I argued A LOT during those 4-5 months. The first two months were pretty miserable. DH would try every emotional trick in the book. "It would be just fine if you would just let my MIL do ___." but we all knew that ___ was never enough. She, like your BIL, is a manipulative, passive-aggressive, self-absorbed woman. She's narcissistic and a taker. BUT after that 2 month mark hit, DH woke up and smelled the coffee. When *HE* became the person who suddenly had to deal with his manipulative family member all on his own, then suddenly he became A LOT LESS INTERESTED in all of us spending all of our free time with her. This was because.....
- Narcissistic people are emotional vampires and they will suck the life force out of you if you let them.
Now things are much better. DH knows that I mean business. He knows better than to expect me to include MIL on every blessed thing our immediate family does. Happy wife - happy life.
You don't have a BIL problem. You have a DH problem. It is notable that your MIL has kicked her son out of her domicile. Your MIL should have stopped enabling him years ago. Your BIL is a loser. Your DH, however, plays the role of the responsible dutiful son who will swoop in and save the day. Your BIL is treated like the Golden Child...usually, the Golden Child is the loser of the family. The child who can never seem to get it together, yet is also the child who everyone throws money at. Learned helplessness.
Your situation will not improve until you are prepared to kick your DH out and find a divorce lawyer. Your DH is putting his sibling's needs above the needs of his wife and children. That is no marriage.