Sounds like your mother in law wants her little boy back...

Before I was married, I really liked my boyfriends mom...we got along great. After we got married, she got almost competitive with me over my husband. It was a really weird time in my life. It's like she wanted to prove that she was more important than I was.

My husband did the right things and made it clear to her that she needed to stop this behavior.
I think your husband needs to let go of his mom and be a husband first and a son second. Sadly, you will probably come out the bad guy in the beginning, but honestly, you need to stand your ground on this. Or be prepared to have to wait until she's...gone.

I wish you the best. Keep pushing for counselling if you don't have the strength for this (and lots of people can't do this alone)...