I had an affair with my now boyfriend. That was the "gateway fuck up" that led us to a polydynamic.
It was an emotional nightmare. I've written quite a bit about it on here in the past.
Getting through to something workable and healthy for hte group as a whole has been very difficult and only in the last couple of months have we started to really make serious progress (it's been 3 years since we started poly and honesty). The big change was a poster here pointing out that in order to be happy going forward-the "punishment" has to end at some point.
Anyway-not sure precisely what you are wanting to know but I'm more than willing to share. Also Maca (my husband) has posted about his feelings here too...
"Love As Thou Wilt"