mother in law

MIL constantly pissing me off and I thought after having a baby I would have grown some balls but idk what my problem is. 
I'd rather avoid her than address the problem.
She brought my baby to the damn pub and I didn't think of it at first but when I seen a pic on FB with my poor baby boy sleeping on some random bitch, I went through the roof. 
My husband is gonna be nice about it but he's a mommas boy and I'm sick of it. I don't even understand y he always has to have her back !! It's so annoying especially when he JUST found out she had been lying to him all his life about his background. He literally thought he was mixed with Puerto Rican but low and behold he's black and white. I don't understand!!!  why the lies ???