Is there any merit in the time old saying "Once a cheater, always a cheater" or do we believe all people deserve second chances? What about 3 strikes you're out as in baseball? And how do you define cheating? Does he have to sleep with another girl? What if he flirts with his ex over text? Buys female coworkers lunch and occasionally gets too drunk with them off-hours? And of course, no matter what he did to earn the title "cheater," you're going to have confused feelings. The hurt and the anger may come first, but underneath that is love and longing - for the relationship you had, for the good times, for the man you thought he was. So now what?
The mix of feeling hurt and feeling love for the person who hurt you is bound to make you feel confused. You're literally in a storm of emotion and you're trying to see your way through but it's like being on the inside of a tornado, it's too thick to see through to the other side. Don't make decisions while you're this clouded and confused, wait until you're clear-headed and then you won't be as likely to regret the decision you make.
No, you won't be clear-headed tomorrow or next week. You might think you're POSITIVE about what you should do but that's like when you're drunk and you're POSITIVE you need that tattoo or two shots of tequila. You're not ready. Tell him you need to take a break. You need breathing room to clear your head and make up your mind. (P.S. If he's enough of an asshole not to wait for you during this break, you got lucky, because he made the decision for you two and you just got away from a major fuckboy).
While you're on your break, try not to think about it too much. This sounds counter-intuitive. You have to look at a problem to solve it, right? Well, not necessarily. Take time for yourself. Do things you enjoy. See your friends and family often. Go on a date if you want to. But don't agonize over what happened, not yet, and don't rush. It's his turn to feel pain as he awaits your decision.
Once you've had a healthy amount of time, assess what you truly want. Have you been happy, perhaps better off without him? Or have you missed him every day and not an I-miss-him-if-only-we-could-go-back but I miss him and I want to tell him that we can make things better. As hard as it is, if you're going to spend time wishing he hadn't cheated, you aren't going to be able to reenter the relationship. However, if you're truly wanting a relationship with him and thinking about a future with him rather than dwelling on the past, you may be able to offer a second chance.
At the end of the day, it's your relationship, and it's up to you whether you can move forward and have the same quality or better quality relationship again with this person. My advice is patience. You might decide that you need complete loyalty - which you absolutely deserve - and would rather be alone right now than with someone who would hurt you that way. You might also decide that you understand what drove him to weakness at that moment and are confident it can be prevented from happening again.
Video: How Women Feel About Cheating