The big mistake was getting so drunk that your priorities got all messed up and you missed out on the hot chick.
I can't really blame your room mate too much. A hot model acting frisky is hard to resist.
I don't see him as having an excuse for eating your pizza though.
Even if your room mate didn't get with her, the night still might have ended up with both you and the model passed out, with no sex, because of your silly angry bird/ pizza maneuver.
But feeling bad about what you did when you were drunk doesn't make sense.
It's letting yourself get that shitfaced drunk in the future that you want to avoid.
You can probably drink one-third to one-half as much as you did and still have a great time and generally avoid this type of thing, and might avoid much worse things too.
Maybe your roomate is an asshole, it's worth considering. If he does this with pizza and girls, what will happen with bigger things?
Also, how do you know they didn't film you getting fucked by a horse while you were passed out? I think there is at least a 50% chance that that happened, and that the horse actually ate the pizza.
You probably should have a strictly "no-horse" policy in your dwelling.
good luck to you.