Wouldyou treat someone you loved like shit?? And cheat?? I didint think so. He doesnt love her...he never did. Go for it...show herhow she is supposed to be treated.
If she wanted to be treated well she would be with you and not him. This is only going to end one way. She's going to tell she loves you like a brother, and that's a bad thing unless she's the sister of the guy who wrote the last post, and she's going to want to be just friends with you while you get to listen to her tell you what a jerk her boyfriend is. I was 19 once. I've been there.
I'll bet you're never going to have sex with her. I would take those odds to Vegas.
You know what else I would bet on? After you pick her up, take her to dinner, pay for dinner, and buy her roses, you're going to hear this exact phrase "We need to talk".
After that you will hear either "I really like you, but..." or "You're a nice guy, but..."
There's a 100% chance the next sentence that comes out of her mouth will contain the word just immediately followed by the word friends.
Women all follow the exact same playbook and your story isn't going to have a different ending. Spare yourself the grief and just forget about her.