So this is actually an FML. Why is it in nearly??

Kick his ass and make him tell the truth and if he doesn't tell him he'll be located in a ditch far away from where he is now

I assume you have the paperwork to prove your work is yours or can get signed statements from people you worked with over the summer. Get the Dean of Student affairs office involved, get the Dept chair involved, basically use your rights and resources to get what is rightfully yours. File a plagerism claim with every office on campus that you need to. Plagerism is a serious offense and college officials take it very seriously. If he copied a typed document you can suggest to whomever you make the plagerism claim that they check the origination date/time of the document on each of your computer's. Don't tell your ex friend what you are doing even though deleted files are never truly deleted it just makes it a bit harder in the first get go so try to avoid that with him. FYL.

I'd be so pissed, I'm sorry that happened to ya

Whoa. That sux sooo bad. The betrayal must feel so awful. Time to make a list of every possible way that you can find to legally, non-violently and ethically acceptable way to get this person invalidated. Start with the school. Include police, social media and anything else you can to prove your case. Do the things that provide you with a pay off, and let the rest go. Your ex friend will have their own negative karma to deal with.

This can be fixed. You can get it and he can be thrown out. Follow the given advice and talk to EVERYONE.