What a rare treat! A husband who actually stands up for his wife in the face of disrespect!
June, do not apologize. Your MIL was the rude one and apologizing will only feed in to her delusion that she was wronged. If she wants to miss out on knowing her grandchild, that is on her.
However, if you feel bad for your husband's predicament, you could try having an honest conversation with your MIL. Tell that while you're not going to be her doormat or punching bag, you love her son and that's why you want to declare a ceasefire. This is contingent on her good, respectful behavior and both of you staying out of each other's way. This only works if she merely dislikes you and is not completely insane. If it is dislike, she may take your offer of a draw and quietly reintergrate herself in her son's life.
