I’ve been in a relationship with a guy for 6 months now.
I think you were reacting, not OVER-reacting. From all you posted, this guy takes you for granted and does not set you high on his list of priorities. There doesn't seem to be any confusion there, that's just the way it is. If you like being treated like a doormat, stick around and wait until he leaves you for someone else. Otherwise, reevaluate your own value, assert yourself, and dump his ass. Just the humble opinion of a girl who does not take any crap from anyone.