My mom is very verbally and emotionally abusive. It escalates when my dad is in hospital. What should I do?

My mom has always been very high strung. She is very smart and able to be quite emotionally manipulative. It is a personality disorder. I dealt with it all my life, partially because there were no real big issues that came between us. Now that my dad is in the hospital, issues are there and she has her fangs out.

I believe that there is good cause to believe that my dad is in the hospital because of one issue. She feels strongly that it is another issue. So, when the doctor calls her to give her an update and it supports her issue, she will call me and sound hysterical and abusive. She also gets irrational when she is hysterical and asks me to do things that are absurd. Since I have a family of my own, I cannot just drop what I am doing just to humor her anxiety. So, when I refuse to do what she asks right away, she tell me something horrible emotionally and hangs up on me.

I usually drive her to the hospital, because otherwise she must take a taxi. I want to go to the hospital tomorrow to see how my dad is, but I don't want to drive her or be at the hospital when she is there due to her abusive, bad behavior.

What should I do?