I am about to get married, but just found out that he has been cheating on me. Should I forgive and go on?

I love this guy very much. We've been dating for almost a year now and he already proposed. I said I do, but now, sometimes I think I don't. The problem is that HE KNOWS I love him very much. And then he cheats on me knowing that I will probably forgive him later. He just admited he has been seeing an ex-affair when I was away to my parent's house. He begged me to forgive him, and I actually do. The problem is that I don't know if I can trust him anymore. And I'm afraid that if I get married to him now, things will only get worse. It's not nice to say, but I'm a bit tired of forgiving. At the same time, I'm tired to search for the perfect man, who won't cheat on me. What should I do? And most of all... what do you think: should women forgive???