I've had a mother-in-law (I call her Mothra, Queen of the Morons). I think that's where the problem actually starts. Don't have mothers-in-law, especially of differing political persuasions.
It got REALLY bad in May when we were there for only 1 night, thank God. A lot of what they do they wait until he's not in the room so I try to never be alone with them.
I told him after this last visit that he either needs to tell them to cease and desist on talking politics at all or let me open up on them. He did agree he would have a 'chat' with them before we see them again.
Actually he can take the kids and visit without me, that would work out real well IMO. I don't care if I ever see them again. Thank God my family is reasonable.
Sounds to me your MIL is simply regurgitating what the MSM and her liberal friends are telling her. Thats what the situation is with hubby's family. It's all emotionally based, none of it is based in logic. It's usually a waste of time to try to argue with these types, although some like to do it. They are so narrow minded that they don't want to be confused with the facts.
Who knows? Maybe you can talk some sense into her this weekend.
MKM