My friend is dating my ex

This is direct violation of bro code. This guy is not your friend. Cut ties and burn that bridge there is no turning back from that.

Don't be a fucking pussy all your life, go and knock him out.

Be the better man. I'm not saying be his friend cause he fucked that up the moment he went for you ex without saying anything to you first. I'm saying be friendly and civil and show that you don't give a fuck and your over it (even if your not). That way they can't complain about you and everyone who knows what happened can complain about them and talk about how your such a cool guy for taking things so well. and get a girl friend asap just to show that that bitch never meant anything to you. Best of luck and make 'em pay! ;)

your 'friend' is a straight up coward, couldn't even say anything to your face. not your friend, probably was never your friend, obviously jealous of you to some degree and probably for quite a while. most likely not telling you is a setup so that they remove you from their lives and take all of your friends collectively with them, they want you to come to this party so either you A) Look like a chump--when you do nothing and look foolish or B) Act like an irrational asshole--when you go buck wild and start trying to choke one of them.
Straight up, get something hotter than the ex and focus all your attention on her, bypassing the party for this girl is optional as well as most other men would completely understand not going to a party when you're trying to get some ass.
And while you're at it, go brush up on your boxing/fighting skill-set, this story wont be the end of it, you're probably dealing with two people who are more petty and attention whoring than you realize.

Do what it takes to keep both of them out of your life and keep moving forward. Ask to sit somewhere else and don't associate with them. Anyone who would do that to you is not a friend.

he was probably frogging her before you 2 even broke up.

that girl is a bitch and your friend totally betrayed you.

Ex is the word not your problem who dates her now although u should wish them the best and move on not trust the dude again

well do you still have feelings for her ? First of all he's a dick..that's unquestionable, and he's not a good friend. I thought guys didn't do those kind of things -bros before hoes and stuff-. I guess it depends on the person after all. And shes a stupid bitch too, sorry for saying that but its true. I would never, and by never i mean NEVER do that. You don't date your ex's friend! Who does that..its weird it makes things complicated you will probably hurt someone,there are like 100000 other guys you can date. The only situation in which it would be acceptable would be if you have all talked about it and its been like years after you broke up, i guess. If you do have feelings for her, then the whole thing is even more messed up, if you feel the need to "fix" things between all of you,you should confront them and tell them that you thing they acted like jerks, they may take it the wrong way and make it even worse though. Or you should completely remove them from your life, act like they don't exist and soon enough they wont really exist in your eyes. Let karma do its job, it will fuck them up both eventually. Good luck. (sorry for my english)

So what an ex is fair game your relationship with her is over so if she wants too date your friend are you really going to be able to stop a relationship between two consenting people. Why can't you remain friends and since it's over it's not like you're interested in her anymore. My friend dated my ex and we are still friends. This whole bro code is bullshit life is about what the individual wants so get your head out your ass and move on like she has.