Should I stay or should I go???

I'm 31 have never been married but have two kids from two different fathers. Wow. Writing that out just sounds terrible. I am currently with the father of my second child. We got pregnant 3 months after we started dating, moved in together after 5 months, and have been together for the past 1 1/2 years. For the most part, our relationship is great, he makes me laugh, our life is wonderful, he is loving and affectionate and compliments me all the time. But...he was recently divorced prior to us meeting. He was cheated on, constantly lied to, and even after all of that, he is still paying for his past relationship through alimony (she never worked), child support, and because we are in CA, she got half of everything. Needless to say, he carries a ton of baggage. I know he loves me and I love him. But, I want to be married someday soon and he doesn't think marriage is important. He thinks I want to marry him so I can take advantage of him the way his ex wife did. I love him but I know I want to be married someday. I'm afraid if he never marries me and I stay with him, I will grow resentful and angry towards him. I've explained to him many times that I don't need him to support me, I have a good job and although I live in his house, I pay him a monthly rent (about half of his mortgage), buy the groceries, split our day care cost, pay for my own bills. On one hand, I don't want to become an old bitter woman and have regrets because I never married...BUT I don't want to be selfish either...I can't break up my "family". I've made that mistake once before...but it depresses me to think he'll never marry me.