Yikes. The BIL. I wouldn't want to have to see him or interact with him. My BIL has been so "supportive" of my H. He was the first to tell my H to do what makes HIM happy. I'm with you--I'm not so sure I'd like your BIL's idea of support.
Go with what rr22 said. That seems like the best plan. As for the MIL, stay on her good side! That's what I'm trying to do right now with mine!