It's not possible to give you a definite answer. We would need to literally observe your relationship in person just to have a somewhat accurate opinion.
Did you find out he was cheating because he acted suspiciously, and you dug? Did he tell or let slip his extracurricular activities? I'm assuming the first.
So you supposedly, and perhaps rightfully so, got angry. Was there guilt? There are many ways to express guilt--did he cry or become extremely defensive?
In any case, you were hurt and put up your wall, pushing him away, and now you've been text-teasing for however long. Perhaps his other boyfriend got boring and he's attempting to rekindle things with you, or maybe he's been giving you time to cool.
I do agree that most people that cheat will probably cheat again, but to some cheaters, cheating really isn't something as breaking as others make it to be. They see someone desirable, have sex, and then go back to the relationship mindset afterwards knowing they've got a great boyfriend. This may or may not be how your ex thinks.
He sounds like he wants back in though. If I were you, I would go back into the relationship guarded and prepared, and if he seems sincere, then keep going. If you ever feel like a cheat-wave is coming on, bring up the topic of an open relationship. I know I know, open relationships

, but if each of you is honest about who you're having sex with then at least there's trust. I hate to be a downer, but it seems to me most relationships don't last anyway and at least this way you'd have trust.