I agree with kindachaotic.

I would also commend you for trying to find compassion for what may be causing her to act that way (e.g. pain, worry, etc).

I find it really hard not to react when people treat me poorly. I have to literally clamp my lips together sometimes! When I feel a strong reaction like that with family members, I try to react with the thought "I wish you happiness" in my head. Note I said "try" Mostly I just have to walk away.