Help, need opinions please.

Okay ladies! This is going to be a long post but I need opinions. I dated a guy for 3 years, that I have known all my life, we were always fighting about something, we broke up numerous times, but we did have our absolutely great times too. But we did end up calling it quits for good. About six months after we broke up, I met this guy, we started talking and now we’ve been together for about 2 years, we’re building a house, and we’re planning to get married sometime in the next few years. So in the six month period between breaking up and meeting my current boyfriend, me and the previous guy we’re still talking, as friends, “helping each other cope” (it actually just made things worse), and of course it ended up being a little more than what we both planned....a few times. The last time we “seen” each other was about a month after meeting my current boyfriend. Me and my current boyfriend were talking at this point, nothing serious, but obviously it turned into something serious. As soon as we started getting serious, I cut all ties with my previous boyfriend. I have never told him about this. We’ve never really talked about it so he has no idea I had seen him after we had broke up, and especially not seen each other like we did. Tonight, my previous boyfriend showed up at my work, I treated him like any other customer, didn’t have a conversation, nothing. But this made me start thinking about it again. This was over two years ago, but I feel terrible about it. Should I talk to my boyfriend about this, or just forget it ever happened? I’m afraid it will mess things up, and he would wonder what brought this up, if I tell him, but I’m afraid if he were to find out later he would get mad anyways, and potentially cause even more problems. He has a short temper, so I don’t know what to do. Please help ladies!!