NZ, a few people have already stated my sentiments. I was an investigator for a long time, and have done my fair share of 'Spousal Investigations'. Here's the thing, mate...it's not necessarily true that she'll do it again. Maybe she will, and maybe she is genuinely sorry, and it won't happen again. BUT, and it's a big J.Lo BUT!...You won't be able to look at her the same.
If she goes out, you won't trust her, will worry SICK over where she is, who she's with, and what they're doing. Also, every time you touch her, or try to be 'alone' with her, you'll picture them in your mind. It'll comsume you. I've seen it, and...I've been there.
I am SO sorry that she did this, and what you're going through...but you'll hurt for a while, then feel better. It's best to end it now, and start the healing process (also known as a 3 day bender) rather than try again, only to end up just as I have described, then have to get over her again.
Good luck. rely on your family, and your mates, including us, to get thru. You'll make it. trust me.
And if that doesn't work, post a thousand flyers with her picture, and a warning not to date the skank!!!