Thanks for the paragraphs
Number one opinion? Don't cheat again. Stop now, it distroys EVERYTHING. He doesn't trust you because that was never rebuilt the first time around. If you LOVE your marriage, family etc. go into therapy and get your relationship sorted out before opening it up or I would venture to say you will have nothing. I suggest starting with the "forced" sex issue and trust issues.
Leave the friend alone. Your are playing with fire big time! Again, you need to either find a way to work together or divorce. You seem to be in deeper than your realize, but then I have VERY strong views on cheating that incluide little tolerance. I don't believe there is ever reason to cheat.
Check out some of the other threads on "cheating" and "affairs" in the search engine. Look under tags. Cheating and poly don't mix. I question whether or not you are poly as I don't hear love for anyone you have had or want to have sex with. If there is no love, it ain't poly.