What a f***ing wench, you are better off without her mate. Anyone who cheats on you after you agree on commitment can GTFO, doesn't matter how hot they are, how much you love them, eject them out of your life because people like that are poisonous.
If you treat someone right and they cheat, it shows weak character, weak morals and immaturity. None of the stuff you want with someone.
Even if you can go out and get girls I wouldn't just now, btw. Easy to descend into a spiral of getting with loads of girls to ease the pain and then you just end up with an STI or another s*** rebound relationship.
Instead just focus on your buddies, your hobbies, your family and the gym. Make yourself #1 for a month or two, and then you might be ready to go and find someone decent again.