Can't Stop Fantasizing

Just to get right to the point. I'm engaged and getting married in a little over 3 months. I'm starting to not just get nervous but have the little devil whispering in my ear a lot lately. Now this is my first time getting married. I honestly wasn't sure if this would ever happen. I also have a bit of a history of being unfaithful to the people I had dated in the past. I haven't actually cheated on my fiancé, we're coming up on 4.5 years soon. But I have been actively fantasizing of very specific people every single day. I'm so torn up inside; it literally breaks me every day that I keep fantasizing and want to sleep with these people. The old me would have probably done something. And I'm sooo tempted. Two of these people I'm fantasizing about I actually talk to kind of often. I know I shouldn't. But I actually consider both of them a friend. I can talk to both of them literally about anything and everything. One of them I have a history with, and we used to have a lot of fun if you know what I mean. But that was few and far between. But I regularly think of him. And he knows that. We tell each other the things we want to do. But we never do anything, just text. And we build up our adrenaline every day when we chat. I talk to the other guy on Snapchat and we have texted and snapped certain things. Although he's engaged too. We have been trying to not talk about sexual things but I can't help but fantasize of him. Last night I couldn't stop thinking of him, looked at his picture and had the biggest orgasm. I'm feeling soo hypersexual and feel the need for this crazy adrenaline. The old me is starting to come out again. And now I'm scared. Because I don't want to ruin my relationship but I'm sooo tempted.