Wow, I think we should "start fresh", meaning you can date other people as long as they're not the person you want to date, even though I have no personal problem with her? That just seems really emotionally immature and un-compassionate of her. And wimpy of him, since as you said he could have taken more of a stand about it.
If she's got these major control issues, and he's willing to let her run the show in regards to his outside relationships, you're netter off with it being over. Rather than feeling victimized by their messed up decision-making process, just remember that you in fact were the one that broke up with him. Try to think of that in an empowering sense -- you *chose* to walk away. Now it might have been nice to get it back, but in the end it was still your choice to leave in the first place. Your mileage may vary, but I feel like that could give you more of a sense of control over the situation.
Do your best to move on, and don't enter situations with a veto power in place next time. You're going to be ok.
The major players. Me, under-30 bi female. Gia, girlfriend of 3+ years. Clay, new boyfriend/dom. Davis, ex/"it's complicated."
The supporting cast. Eric, Gia's husband. Bee, Gia and Eric's toddler. Dexter, Gia's lover. Helen, Eric's lover. Izzy, Clay's partner.