First of all, you didn’t do anything wrong. You’re free to date whomever you want, since you’re not really in a relationship with anyone.
If the guy you’ve hung out with is upset that you hooked up with someone else, that’s his problem. He can’t claim you without even asking you out for a first date! You didn’t cheat on him. You’re playing the field. If he doesn’t understand that, he’s not boyfriend material.
That said, I can’t tell you if this ruined your chances with him or not, because I don’t know if his hearing you hooked up with someone else is going to make him suddenly uninterested. But it may make him rise to the competition and want to make you his own, rather than share you. Sometimes guys need a little competition to make them step up their game.
I would not advise you making the first move with this guy, however. He knows where you are. He knows how to reach you. If he wants to ask you out on a date, he most likely knows how to do it. If you do run into him or see him around, you can be flirty and available, but don’t throw yourself at him. Make him work for the date — his reward will be all the sweeter for the challenge.
