My mother can send me into a rage for the rest of the day after one of her trips, or a deep depression. Like you I cannot completely avoid contact, but I do try to severely limit it for the most part. Reminding myself she is a lunatic helps sometimes, but at others it is no use:(
Yes, sometimes she could almost trick me being such a lovely warm person, but there is always that other life sucking side of her. The last time I visited her she ended up leaving the house and wouldn't come back till I had left. It sucks, but I've come to learn what to expect.
Limiting your contact is your best bet. Accept the past but realize your grownup now. You have much more control.
just see a doctor!