Please help, I need relationship advice?

Sorry if this gets long but I am really upset. I love this guy I've been dating, but I found out that even though he had feelings for me and I had feelings for him and we both knew, he had some random hookup with some girl. It really hurt me. We weren't together, but still. It's a matter of the fact that he did it. We've known each other for awhile not and I'm not quite sure what to do. I love him with all my heart, but we did break up. He doesn't want to lose me and I don't wanna lose him, but I also don't just wanna make him think it's okay to hurt me and get me back without question. I've had experiences with that and can't deal with it. What should I do, or say? I really need help. He is the one I wanna spend the rest of my life with, please give me some advice.