Most Helpful Guy
Honestly anyone who has cheated is capable of doing it again. I would be worried also. If you feel uneasy about it I would trust your instincts over what someone else is telling you. regardless of if he cheats on you or not feeling that way is no way to live your life. You should want to be with someone who makes you feel more secure not less secure.
Most Helpful Girl
Agree with @Cyfris. Unless you don't care about him at all, or you take him as a side fling, his cheating history and all those things shouldn't be ignored.
You won't feel secure and will be reasonable to overreact , if staying that way. Do go there. Trust me.