My boyfriend mom has got me fucked up (excuse my language) if she thinks she's going to treat me nasty and put it in his…

My boyfriend mom has got me fucked up (excuse my language) if she thinks she's going to treat me nasty and put it in his head that I'm trying to take his child away from him. She can't stand the fact that we're working on things and back together to raise our baby and be a family. My boyfriend and I have already discussed that if it continues, she'll be cut off and I feel bad but she's causing unnecessary stress.