I'm paranoid about what he does without me?

if i were you i would be honest with him or leave him....he obviously doesnt know what commitment means! he's just using his recent breakup as an excuse to keep you around...its not okay for him to throw parties without inviting you because he should have nothing to hide from you...if he seriously cares about you then he will want the relatioship to work... but if he doesnt want you to be his girlfriend then your just wasting time..good luck