I do believe it's possible to work through cheating. Especially if you trust that it was a one time thing. However, there are so many steps to go through and then to be able to completely forgive and truly move past it, not letting it harass you any further.. It's not an easy task, and if you find that you can't forget about it, or that it keeps rearing it's head whether now or later because of how his actions in the past continue to make you feel then it might be better to just cut your losses and start anew. You don't deserve to have to continually worry or be concerned about if he is cheating or not cheating.