You get over it by reminding yourself what you already know: not all men are alike. Then you get on with your life.
Just because a guy cheats on you doesn't mean the next one will. Don't let one jerk destroy your faith in the male species. That's not fair to yourself or to the men you will date in the future. Every new guy deserves a clean slate, and you deserve to be excited and optimistic about every new relationship. If you expect the worst, the worst is what you will get.
Yeah, you got betrayed. You aren't the first. I know it hurts, but such is life. Bad things happen. People hurt us. That's on them, but if we let them steal our joy, that's on us. The past is the past--let it stay there.
If you watch football you've no doubt seen a player take a brutal hit and then pop back up immediately, as if to say, "Pffft. Didn't hurt a bit." That's mental toughness, and you have to do the same thing when someone knocks your ass into the dirt. Get tough, get up off the ground, and get on with your life. It's a matter of willpower, really. Resolve to remain positive and hopeful about your love life. Whenever insecurities try to sneak in, slam the door and tell them to piss off.
I'm sorry you got hurt, but it's done. Move on.
Thanks for the question.