It sounds like you're in the US. In that case you MUST file an ASRS as soon as possible - like NOW. Just search for 'NTSB ASRS' if you don't know how to do it. That SHOULD protect you from certificate action (i.e. losing your license) as long as you can show it was an accident and it was the first time. But you only have a limited time (10 days I think) to do it.
As others have said, your instructor is in deeper doodoo than you are. For one thing his livelihood depends on this, and for another, this is exactly the kind of thing an instructor should be keeping an eye on. Whether he would be considered PIC is a judgement call for the FSDO, as long as you have all the ratings and qualifications needed for the aircraft. But it's very likely.