I think the hardest thing to deal with, other than overcoming the feelings of guilt for not picking up the phone every time she calls, is dealing with the fact that I can't lay out the full reasons that I don't want to have her over right now or want to talk to her in the hospital. It wouldn't help, and it would only set her off more.
You're right that trying to have a rational conversation would set her off and escalate the situation. Can you lay out your reasons here? Many minds working together can perhaps help you find a path through this current crisis

. At any rate, let us know how we can best help.