Okay, you are both very young. So you know, at your age, your brain is still growing so you don't really have full control over your emotions yet. Hard to step outside of your own head, but realize that your feelings really can change on a dime. You can't have had many relationships at 19. You don't know what you don't know. This translates to you as - relax.
As for him, he's very young to have gone through such a brutal-sounding relationship. He definitely needs time to relax and recover. If you really like this guy, back off. Treat this as a fun relationship w/good sex. Turn down the expectations. Not much else to tell you, really.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh