Eighty people is a lot to feed! I have catered from Pompei a few times and am always happy. Their pizza trays are huge (sheet pans), but you can also get pasta, Italian sausage or beef, etc., to add variety to the menu. Their catering menu is online. It gets pricey, though. I'd suggest getting a veggie and/or sandwich tray from Costco or Jewel rather than a restaurant. I'd try to avoid fried food mainly because it doesn't hold up as well. For my son's bday last year, I catered from Smoque BBQ, and it was a huge hit. I only did brisket and pulled pork (no chicken or ribs) and opted for the mini sandwich buns knowing that people would try both kinds of meat. One of the play spaces I take my kids had business cards for birthday party catering, and there was a place that had a hot dog cart. I thought that was a great idea because kids and adults will eat hot dogs. You can probably find someone to do hot dogs for a lot less money in an aluminum pan rather than going the hot dog cart route.
See what you can get at Costco to save some money but only if you have people who can help you out with bringing stuff. It's a kids party, so I don't think people have great expectations, but it is good to have a little variety to accommodate tastes and preferences (like vegetarians) while keeping the menu simple. Maybe 1) pizza and pasta (marinara sauce in case there are vegetarians) or 2) hot dogs and sandwiches/wraps? Either get huge bags of chips from Costco or those boxes of individual bags of chips.
If you're getting too stressed, your menu is probably too complicated. You've got a lot to plan and it will be busy, but you want to be sure you'll be able to enjoy your son's party, too!
Good luck!!