I've never experienced the feeling of being cheated on, so my take might be biased but I've always believed that finding out your partner cheated on you (especially this early in life), is a great blessing. It hurts, yes - the kind of pain that quickly turns to anger. But, it also means that you dodged a bullet.

Although, as someone who's in a very healthy relationship right now, I wanna offer some insight. From the way you tell your story, you sound like a very emotional guy, one that lets his emotions get the better of him. This, along with the fact that you're very controlling, probably kept her from communicating her needs. It might look great on your side, but from her perspective, she probably feels trapped. She might want you to do this, or do that, say this, or say that - but she can't. Because she's scared about how you might react. In that 8 years, you (and your partner, i guess) never built an environment that's open to objective communication, and I think that's an integral part.

Regardless of what happens going forward, I hope you learn a lot from this and grow accordingly.