I am so sorry you are in this situation.
My mom is similar. She wants me to come home to visit but then is extremely abusive when I am there.

I agree that your siblings should take up the slack while you are gone, whether they want it (or your mom wants it). They can even do things like rotate. The ones far away call in the morning, and the ones near by stop by in the afternoon.

You need to take care of your first.

I hope you get a lot of good work done at your program.