Anyone have MiL advice?

What she is doing is a clear message to you that you and your child before her son is not and never will be good enough! Screw that. I would take a stance and show her what respect is all about. Turn the tables. Be silent. Lose the loser. And when she sees the error in her ways never let her forget what a privilege it is to be a part of her sons life with you and yours. With your husband to back you. Period! Good for him. And you.