mmm...so she had a decent relationship with them while you were still treating her like crap? But not after she got tired of it. Sorry to 2x4 you, but you seem to be backsliding into blame, and away from the sentiments you originally expressed about realizing why thinks went the way they did.
I would be careful about using your parents for support. I think MWD talks a lot about this in her books, about how family are not always helpful because they can't separate their feelings from what may actually be best for you.
I realize it's very painful to see your child hurt this way...but I think it's a bit immature and curious that they are ignoring your comments that "you weren't as perfect" as they are holding you up to be. Do your parents kind of have a fantasy view of this situation? Would it be typical of them to say it's all the other guy's fault? Because that won't be helpful in the long run.
Reconciling and blame can't coexist.
I just ask this, just wondering, because I've watched my aunt sabotage her son's relationship more than once, because she "loves" him so much. But she really just can't stand to admit her kid could have done anything wrong. That might not be your case at all though. Just curious. Something about you "reading their cues" and going along with them.
Perhaps you should just sit down with them and say, look, this could come up again, and what is your opinion on how it could be handled. Because how it affects the KIDS is more important than how it affects your parents.