CTH... I hate to bring out the 2x4, but in this case, well, I can't help it.

You are the parent, you have to put your daughter's needs above yours, and you blew it, in my opinion. She was talking about her Mom's... you needed to listen and let it go. Not tell her you didn't want to hear what she had to say.

And it just went downhill after that. You succeeded in putting her in the middle, you just can't let that happen.

As CG said, the answer is detach.