While i do agree that bullies are pieces of shit that only deserve contempt, i do also think that people should be allowed to redeem themselves. And if they do that with their heart in the right place, then i would personally willing to let bygones be bygones.
I mean there are levels to that aswell. I'm inclined to give people a second chance as long as it didn't involve some form of bullying, egregious lying or manipulation. In either of those three cases, it ain't happening because you can never trust those people to tell the truth.
Whether that applies to this specific situation or not is irrelevant however, she did some horrendous shit and sometimes you just need to learn that there are consequences even if you didn't do it out of choice.
Though I will say that I'm pretty extreme when it comes to those specific points because I've just had way too many people like that in my life thus far.