As a guy, I strongly recommend leaving him. I’m not proud of it, but I cheated on my college girlfriend and it ended so badly. I loved her, the first year was amazing. She was the best. Until I went out with the guys one night and ended up going to this random girls house. It was invigorating, it was so hot. I completely forgot I even had a girlfriend, until the next morning… I kept it from her for months. I loved her but she wasn’t enough for me anymore. Just sneaking around made it even hotter. But yeah, once I got away with it once it became a pattern. She ended up finding out on her birthday… I regret it now, but honestly only because I got caught.
Walk away, do not take him back. You may suffer the loss of an idiot, but you will allow him to learn a lesson, which will hopefully help another woman in the future. Forgiving him will only show him he can walk all over you. If you never look his way again he will hold you dear as the one that got away.
If you decide to forgive him, you will doom yourself to a life of constant worry and live a life in constant anticipation of disappointment.Unfortunately, love is not all you need, you need respect too. He may love you enough to stay with you, but he doesn't respect you enough to remain faithful. If you welcome him back with open arms, he will eventually cheat again. Ask yourself if you are prepared to babysit a grown man to ensure he won't repeat his mistake again.