BM,
I understand your concern for your D15 and her not getting hurt. The reality however is that she will get hurt no matter how you end your M (if indeed you do).

As for your H being a nice guy and being reasonable in a D. That's exactly what I thought about my H but look at what he is doing to me now.

FWIW I understand your pain but the phrase 'damned if you and damned if you don't ' very much springs to mind in your sitch.

Good luck

Me 43
XH 45
M 2.7.88
Divorce 7.10.09
Kids D20,S17 & D15