NEED FOR ADVICE

Hi girls! So, almost a year ago I started working at a cinema, and I quit my job like 5 months later. During my time there, I had this HUGE crush on my supervisor, but at the same time, a guy who used to be my co-worker (let's call him C... he quit earlier than I did) asked me out, and so we "kinda dated" for like 2 or 3 weeks, and it didn't work out. Even though we stayed "friends", we completely stopped talking to each other. As for present time, I'm currently dating the guy who used to be my supervisor! We've been together for almost 6 months, and we really are in love. The thing is, 3 weeks ago C started talking to me again. We've had little conversations over fb these past few days and, we were really good friends before dating, and so I missed that. But I also feel really bad, I love my boyfriend, and I don't have feelings for C, but it just feels kinda wrong to talk to him... I just don't know why he is talking to me again... 
I'm a little bit lost here! What should I do? Should I tell my bf C talked to me? Should I keep it to myself? Or should I stop talking to him?
Thanks!💖
Btw, this is me and my boo🙈😍