Mono and I talked about your situation last night. We disagreed on several things. But here goes with my opinion, anyway.
Trevor said he felt as if he were cheating, right? I would suggest that he guessed when it came to understanding your point about it all, in terms of it being about love, not fucking each other's wives. It probably seemed like a great idea at the time, as he didn't think he would react. He probably thought it would be fine to "give" Amber to you, and would be fine with "taking" Jolene, in return. He missed your point and, not only that, he got all excited about the sexual act, had sex with Jolene, and then realized what he would lose, which was Amber. He got emotional, which was your point. It was about emotions for you. It turned out that he actually cared about that enough to say stop!
I agree, he's an asshole. But give the poor man some credit. He saw where he went wrong and is working on it. They both are.
How many times have we said on here that poly relationships challenge EVERYTHING? I really hope that at some point your anger subsides and you are able to empathize with them, for yourselves, more than anything.
Perhaps you can use this time to better educate yourselves on poly and all it entails before proceeding with another crush/love interest.
Too bad you didn't get laid. I gotta say, that really bugged!!