CAbayarea : Welcome to SR.glad you found us!
Good advice from BigSis. To get an idea about interventions, may I suggest:
http://www.lovefirst.net.
Best of luck to you all. I have yet to have any of my AH's problems seriously.......they assume or want to that it is me and the kids that "make" him. Still.......it is AH who has to choose.
Stick around; this is a great place for imput and support for you and your husband,despite what your BIL decides.
p.s. Don't forget about your SIL and the kids. They need support. Maybe you could point her here or AlAnon (or both).