If you have been cheated on, you need to cry. That's step one. Cry it all out, unabashed and without control......privately, NOT in front of him.
You might want to throw in a few "heartbreak" songs but only the ones that promise you will survive and what not.
The next thing to do is to burn his clothes!!!! I'm kidding. (Hollywood dictates that you burn his clothes....who comes up with this stuff, anyway?) Don't do that. Mainly because it's too much trouble and because you have better things to do. Not to mention that punishment only actually strikes a note if his clothes are really important to him and cost a fortune. If he shops at Kiton or Brioni (6000 to 50,000 USD per suit), it would make sense but then again he's very likely to replace it without flinching. It goes without saying that you should end the relationship with this boyfriend.
Do not call the girl he's seeing. I repeat do not call or even worse,
the girl he is seeing. It would either result in a cat fight which is just distasteful. Or she could give you the "if you can't keep your man......." line. Alternatively, you could both bond, then dance to Beyonce and Shakira's "Beautiful liar" and go home. You would agree that none of this is time spent wisely neither does it provide closure.
Closure is most elusive after being cheated on. Ideally, an apology should fix it but that hardly comes along and if it does it's usually not sincere. So how do you get closure?
The most popular way is to "rebound". To get a new boyfriend or to have a fling. Unfortunately, this isn't closure, it's just a distraction; an attempt to feel wanted and significant. It's usually not well thought out and is almost always at the expense of the emotions of the new guy.
What you want is suppor, from friends and family and yourself.
Pull yourself together. Dress up and go out. Even if you are indoors. Perfume too.
Try not to hate... it just gives you wrinkles. Skip that phase. Skip the name-calling too. Try writing out how you feel, all the venom and anger on a sheet or a screen. Write it all out. When you read it five years later, you'd roll your eyes at how overdramatic you sounded. I read mine recently. I had to shred it immediately. My French could not be excused.
Wipe out every trace of him; gifts especially. No bonfire necessary. Donate to a charity.
So he's physically gone. He needs to be mentally absent too. You need a hobby. I know I say this in every letter. You do need a hobby; a productive, time-consuming one, that engages your creative mind. Make something, design something. Try a new sport.
Hopefully, you never get cheated on and don't need this letter. However, if you do, don't let this experience leave you wary of men. If it happens with more than one guy, don't become jaded and paranoid. Not all men cheat. It's the truth.
So remember; cry, ignore him and the girlie, get support, write it all out, get a hobby and stay wrinkle-free.
If he comes back and begs, you know what to do.
Ps: don't even think about taking him back.
Disclaimer: Charly is not married and so she's free to cut her losses.