Ok, you said to cut our talk short. In the past, she has brought up that we never talked about our problems-just swept them under the rug etc. I think, she will say something to the effect of: See H, this is what you do, when we need to talk about our M, you just cut and run-not sure how to address that-thoughts???
Give her advance notice when she gets on the phone. "Glad you called. I've only got a few minutes. Things are crazy here. How are the kids doing?"
This solution is NOT permanent, but only for the next few days until you balance out your emotional turmoil.