You have examples of this. Because I've played through the game twice now, and I never saw any of this with Abby.
For example in the beginning of her section, she hangs out and jokes with Manny about how much pussy he gets. She pleasantly interacts with people in the cafeteria, including Manny's father. And the only point of contention is how she and Mel aren't really friends any more. And an off handed comment about what they did. Outside of that, it doesn't get brought up again.
You could argue that much later when Mel calls her a piece of shit, it might be a reflection of her revenge. But that's more likely Mel trying to get Abby to leave Owen alone because love triangles are a thing in this game.
Also during her section she saves the scar kids, but it is never ever hinted that this has anything to do with any sort of regret of her revenge on Joel. She kind of saves them by circumstance after they cut her down. Then she goes back for them later simply because this game wants you to feel like Abby is the hero of this story. That she is the good guy. She plays with dogs and she saves kids, look at how wonderful she is. Joel surely must have deserved her anger because she is just so great you guys.
I don't buy it. It's poorly written and stupidly executed.