Re: What should I do?
So when do you leave? I hope you go there and get a good rest. Here are some suggestions:
If your MIL tries to reach you, have it go through you mother first (i.e. have her answer the phone)
Have your conversations with her on speakerphone in the presence of your mom. If mom’s not around, don’t answer.
Spend Eid (and why not Eid-al-Adha) with your mom as well.
Relax. Don’t take any tension from MIL.
No matter what MIL tries, stand your ground.
Well, 
this will be good for both you and your child.