Thanks, everyone, for your sympathy and suggestions... unfortunately, eliminating these boys from our function is not a viable option. The 3 fraternities involved are the top 3 on campus, and over 3/4 of our sisterhood date boys in these chapters. There's no way they would stand for it. It's come up before, as a way to reduce this sort of thing, but it always falls through.
In the days since, the 2 fraternities that fought in the street have been quasi-fighting all over campus... a group of CDE boys will roam around looking for ABs to start something with, and vice versa. They've been broken up by public safety numerous times. One of the younger ABs, a sophomore who dates one of my sisters, was so riled up after he left Crush that he FOUGHT THE PAPA JOHN'S deliveryman who was leaving the dorms as he was coming in. God only knows what this poor pizza man said to set him off, but the AB literally jumped him and it took 3 brothers to break it up. Quite mature, eh?
We wrote a letter to XYZ about the window breaking, expressing our disappointment in their concern for our liability and disregard for teh well-being of our chapter in allowing a pledge to get so out of control (apparently he was seriously frightening some of my sisters, sexually harassing them, and no brothers intervened). Hopefully something will come of that.
No word on the t-shirts... we're looking on Ebay, though

My advisor called the guy who made them and he felt so bad he offered to redo them at half of cost, about $4.50 a shirt if we wanted. Unfortunately, the chapter is pretty strapped for cash, and the remainder of our social budget is going towards Formal, so we turned it down, but it was a really sweet offer.
Our campus Greek advisor is pretty biased towards the fraternities here... they can basically do no wrong, but god forbid any sororities should have new members wear pins. Seriously, he reported 5 sorority chapters to their Nationals for hazing because of "the obvious segregation between sisters and new members that was indicative of deeper hazing practices." Yet fraternity boys can walk around for weeks dressed entirely in camoflauge, covered in ketchup, mustard, chocolate sauce, and mud, unshowered, speaking in the 3rd person, and never feeding themselves (they must be fed by a pledge brother), and they come up smelling like roses. It's really very unfair.
Grrr.... hopefully things will calm down soon though