more than one

so i have been dating this guy for 2 and a half years and things are awesome and have been. absolutely nothing wrong with him. but i ran into an old friend and we clicked like we used to and he ended up kissing me. i liked it more than i should have. now i cant get him off my mind. i dont want to cheat but i feel like the next time i see him it might happen. its not like i can see the old friend often he was just in town but he's coming back in a few months and wants to meet up again. i know i should say no but when i talk to him my entire body feels like its on fire. i still love my boy friend... im stuck in a love triangle i guess... what do i do?