Don't know what to do

So let's just say this guy (who is 18 and I am 16) were friends with benefits. We had unprotected sex (was my first time too..) about 3 weeks ago. My period ended the day before we had sex. I know he didnt finish inside me but I hear there's always a chase I could get pregnant. I'm waiting for my period but last month I was late. Could this make my period even later? I've already thought about what I would do if I was. The worst part is he is leaving for boot camp in August. And I have strict parents. They already threatened that if he touches me in any way, they would get him for statutory rape.. I'm so scared.. Sorry needed to vent to someone. Any advice?