Girl In Trouble: The Rough Guy I Slépt With Knows My Boyfriend

I'm in a very good relationship with a very good, fun, loving man. Let's call him Francis, though that's not his real name. He's 34, I'm 28, we've been together for about 6 months now. Everything is perfect, we are both committed to building a future together. But something happened recently and I'm afraid it's about to cut my joy short.
My bf's elder brother recently had a housewarming party and I attended the party with my man. Only to get there and meet another guy I had been intimate with in the past! His name is Steve. To make matters worse, my boyfriend knows Steve very well and he even introduced me to Steve at the housewarming party as his woman. Turns out Steve is Francis' elder brother's friend!

What happened between me and Steve happened way before I met Francis. It was at a club in Enugu, a one night stand...

I had gone clubbing with girlfriends. At the club I met Steve, he was really nice, he bought me drinks, we had a good time, I got carried away and ended up being drunk and hor-ny in his car. The rest is history.

All I remember is that when I woke up the next day in Steve's house, I was mortified at what I had done. I practically took off and that was the last time I saw or heard from him till that day at the housewarming party.

I'm afraid that my future with Francis is in trouble. This is his brother's close friend. I'm afraid that this guy may talk to someone about that incident and somehow, Francis will get to hear of it too. 

So, I've been very worried. Should let Francis know, no matter how little, that I ever had something to do with Steve or should I just keep quiet?