Trusting, The more you resist, the more your D will want to go.
And having a teenager around might be interesting for the midlifer. He will have to be a real parent.
As far as you being more strict--trust your daughter and yourself. You have raised her well and she will make good judgments. Possibly more mature than his.
What I have noticed is that in reading these threads, the teenagers seem to gravitate to the non-MLC parent in the end.
As far as exposing her to OW--too late for that. Maybe it's time for her to see the real-life "healthy relationship" that he has, all the fun day-to-day interactions.
M: 16 years Bomb 4/07 OW 20s long gone Divorced 11/09 I remarried New Guy Cooperative r w/X regarding D