You don't. The only scenario where you guys end up having sex is when she comes all the way to your door and asks you to f*ck her hard. I'm telling you man, if you engage even just a little bit, you will get f*cked in turn. She will not only reject you, but also tell everybody about this. People will start forgiving her and see you as the damn beta you'll be.
There is no rationality in that process. They will only see that you came begging and automatically draw the conclusion that she must be not that bad of a person if YOU can forgive her after all of this. It's a lose-lose situation for you. As I said earlier, she has to come to you. This way she will be way too ashamed of her b*tch a*s, she won't even think about telling anyone about your fling.