Oh god, I hear you!
The immensely wise MaryZ on the teen boards, always says that we parents have to look after ourselves, and remember to do something nice for ourselves, otherwise we just burn out.
It is incredibly tough - I am glad I had my DD (17) first, because she was no trouble at all really. DS (15) is a completely different story - even though we thought we had parented them both exactly the same!
DH and I sometimes sit and look at each other, kind of shell-shocked, and say "where did we go wrong", but then we know maybe its not us...its HIM 
We are in another country, and he has exams to enter high school next February. He has mock exams next week, and maybe, just MAYBE we have finally got it through to him that he cannot muck these up. His grades up to now have been APPALLING (he got 3% for a maths test the other day...
) he just does NOTHING but expects to sail through life. Talk about entitled...
anyway, YES, do nice things for yourself - walks, coffees, meeting with friends...I actually do like a drink occasionally and will have a brilliant evening with friends every now again, getting slowly and merrily drunk. I don't care! I flipping deserve a drink 
and
?to all parents of teens