The MLCer will rewrite history and will vilify you to others. I'm sure he's told his mother a bunch of BS and playing the victim right along w/it. Blood is thicker than water when it comes to family and they will believe him because he is family.
Now, about that MIL, block her calls and messages. You don't need to be listening to her spew as well. What's going on in your marriage is none of her business...but after reading some of the stuff she's said, I can understand why your h is having some issues, i.e., mommy issues.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.