HELP I CHEATED ON MY BF!!!!!!!?

Ok so my bf is in love with Me but Im not with him. I'm in love with my bff Ian. He knows ivuse to like my best friend but I thought I was Over him (fine I could never get over Ian) and I told kris my cruent bf that I wouldn't meet another guy. I won't see kris for like 2 n a half months. We talk n stuff. Any way I lay on Ian alot n that's just normal me cause I'm a natural flirt. I was talking to Ian about if and how much he likes Me n he playfully grabs my and I finally say "Just kiss Me if u want to" (idk why I said it) snd he kissed Me we spent the rest of the nite cuddling and kissing. I was looking for a reason to break up with Kris because as a scorpio whT can u say I'm a clingy mofo. My future bf is as well a scorpio. What do I say to Kris? I HAVE TO DO IT OVER THE PHONE. do I tell him I cheated or that I found another guy.? It's my first breakup