How can I be less controlling with my fiance and others?

This is only an issue really with my girl.. I hate thinking that I am, but I know I am. Our relationship has been really rough. I don't mean just getting along wise, you could write a biography on my story, which don't worry, I'm not going to do that here lol. Were both 20 and we've been "together" for a few years, and have been extremely close for 7. She lived out of state for highschool, and came to visit me every month or so. She cheated on me twice, but. I also kissed another girl once. She was with another guy for two weeks in the beginning of getting back together after moving in for a couple months. I've never been cheated on, and knowing that she was pinned up against a wall by her neck by the same guy, when I came to visit her, I well, took him down pretty hard.(I also do MMA fighting and control has been part of my life since I was 5?) Anyway. I am extremely protective of her, which she has told me she loves knowing she's safe with me. She can't drink or smoke and neither can I because I work for the government, plumbing for new navy bases.(I would loose my job if I failed a test) so its mutual not too. She's also extremely "lovey" and forgetful when she drinks, which is why I already know what will happen if she goes to a party. I just can't trust her unless shes with me. We live where kidnappings aren't news, and I live near a court that is mostly housing people of sexual assaults, molestation and what not. I've never trusted anyone but her, but when she cheated the glass cracked. Were now 2 hours away (very close compared to the previous scale) and I feel like if there wasnt this one thing bothering her, we would be okay. In july we are also moving to VA beach. In August she is going to canada, for some girl she met online. shes talked to her for about 4 years, almost everyday. Shes helped her through quite a bit, but Im still her first go to. Mind you, it sound very very bad. Canada for someone she met online? with 4 brothers no mom? anyway.