I would definitely go, if the person cheats that just shows disrespect and that he obviously doesn't love you. If the guy would cheat that would just prove that he doesn't care much about the relationship or about me because if he did then he wouldn't have cheated, I would have been in the back of his mind and he would have rejected the other girl.
I also think that if you stay with him, he will just think Well she forgave me last time and they are kind of like criminals, they will keep doing it only the second time or the times after that he will be more careful about it, hide it a lot more and find ways to cover it up.
Also when someone cheats it creates a lot of trust issues and since it happened once who is to say it won't happen again? So you'll constantly be worried and thinking Are they cheating on me? Are they actually where they say they are? and so on so forth.
Another thing is that cheaters cheat because of their own insecurities, they are selfish and they thrive on having a secret relationship. Plus if you leave a cheater they will go crazy, they will beg you to take them back they will do anything in their power to get you back, not because they love you or because they feel bad, it's because they can't cheat if they there isn't a third party right? So just keep that in mind.
Cheaters will cheat no matter what, it doesn't matter how much you do for them, how much time you dedicate yourself for them or how much you're there for them, they will always cheat to feed their ego.
In my opinion once a cheater, always a cheater. So why stay and continue to get hurt time after time if you can be in a good healthy relationship with someone who will respect you and only wants to be with you?
So for me again, I would definitely leave.