Another Run In

We had another run in with our 16 year old this morning just after 2 am.  He believes as a 16 year old senior he is entitled to be out as late as he wants and we have no right to say anything about that.  I did not grow up with parents so lenient.  As arguments with teenagers often do it turned ugly quick.  We live in a small town where "bad things don't happen."  He claims he wants to be a statistic so that people will say something happens here.  His words were hurtful and offensive to me.  He is defensive about where he goes, what he does, and how long he's there.  I'm getting tired of being a punching bag.  I started to cry and he stood there and said nothing.  Earlier he said he wasn't going to stay past graduation.  It's an emotional threat made on the heels of the traumatic way his sister moved out last summer.  He said I changed.  Of course I changed.  I was in the middle of Wyoming when I got the call about an empty room and a note left behind.  I don't know what it is about me as a mom but my kids can't wait to leave the home we provide for them.  I've heard stories about other kids who won't leave and mine, with no plans whatsoever, can't hit the door fast enough.  I don't know what I did to deserve this level of disrespect from them.  I tried my very best but somewhere along the way they've decided that they can do it on their own and are hellbent to prove it even if it hurts me.  How am I supposed to deal with that?