I have a jealousy/selfishness issue! help! /:?

My first love was perfect, but he turned into this control freak and got mad if I hung out with my friends or any of my family. Well, now I'm in a great relationship. Its perfect, I'm happy. The guy and I love each other. He's sooooo amazing :) but anyways. I have a bad problem. My ex rubbed off on me and now I'm acting like my ex too him. The other day his family was having a cook out for his moms birthday, well he went and didn't come see me at work on my break. I threw a fit. Today, he couldn't come see me because his cousin came out of coma (spell check?) It pissed me off, I know its wrong and I hate it :'( I've cried all day because I don't understand why I can't stop this. Then tonight he stayed at his grandmas, with his family. Kind of like a get together and it made me mad when his friends were staying over there too. Well, I just told him about my problem and he says its fine and that he still loves me and that he'll help me through this, but I honestly don't think I can quit. By telling him my problem, was it the first step to getting better? Or is there something more that I need to do? If so I would love some advice, stories, or help. I really don't want to mess this relationship up. :(