Most Helpful Girl
So if you found out that she cheated and that's when she stopped? So it can be assumed that if you hadn't found out, she'd still be doing it?
In the end, you have to know if you want to pursue this relationship but if I were you, I would not. I don't know if it's right to say "once a cheater, always a cheater" as it seems to generalise a lot and there must exceptions. In your case, however, the relationship only lasted 8 months and she cheated on you for a whole month, and probably would have done so much longer if you hadn't caught her.
If this happened to one of my friends, I would tell him to move on and forget about the girl. I know that's easier said than done, but sometimes we have to do things that hurt us for a bit so that we can find happiness eventually.
You're only 20, almost 21, there are girls out there who will not cheat on you and betray your trust. So I'm thinking it would be best to leave this girl and find someone who doesn't make you feel horrible, because clearly, she does.