MIL from hell

Anytime my mother in law is around she is always criticizing my parenting. No matter what it is, she always has something negative to say. If I don’t let my 3 year old eat 3 bags of candy At 10pm I’m “greedy”. If I scold my son I’m a “child abuser” I’m a stay at home mom, and she always says to me “I don’t know why my son leaves him with you, you’re a child abuser”. It’s to the point my son is now repeating some of the things she says to me. As I was getting dressed the other day he laughed and called me a “fat dummy” I know he got it from her because she is ALWAYS calling me fat (I’m 37 weeks pregnant) I’m not too sure what to do