And has probably gone through the same type of relationship at some point and sees all the signs here. Of course, we all had to learn the hard way ourselves, too. 
Some relationships can’t be ‘saved’. See the writing on the wall and accept it. (easy for me, Lifelong Doormat, to say, but it’s true).
Lest my comment appear too brusque, I’ll expand a bit: assuming that you’re for real, divisibleBYone, and have described your situation truthfully, your boyfriend (if he truly cared about you) would not have put you through what he put you through in the first place.
“I realize now that I was a dick to you, so let’s just call it even” isn’t much of an apology and is a pretty bleak indicator of his future behavior. If he’s still planning to meet with the ex and purposely exclude you, it’s because he’s either having sex with her or pursuing her. That’s pretty much guaranteed.
If you’re okay with that, then enjoy being assistant girlfriend in your new open relationship.