Too much sacrifice, too little return...

My husband and I have been together for 10 years, married for 7. We have 3 wonderful children and communicate with one another very well. I love my husband, though in a different way from the way I loved him in the beginning. I know that he loves me. But I am contemplating divorce because I feel like I've been waiting for the last 5 years. My husband and I dated in high school and when he moved off for college we ended the relationship. 6 months later we reconnected and pursued a long distance relationship and then, once I graduated, I moved to be with him. During those 3 years I sacrificed college, my relationship with my family, my freedom and my security to support him in his effort to get a degree. We argued often about the level of sacrifice I was being forced into to keep our relationship together. I realize that the choice was mine, but I felt that I was given an ultimatum every day to stay and keep our relationship together until he was out of college. If I left our relationship would end. After 3 years and many promises he graduated and told me it would be my turn now. He would support me and I could chase any dream I had. But he didn't seem to mean it or to know what that would entail. Several opportunities for him to put me first arose. Everything from the mundane (he chose to stay with his family and shoot fireworks for 4th of july while I moved us into a new apartment in a different state) to the very hurtful (I was on bedrest with our 3rd child and he chose to back a week long trip for work with a weekend side trip to visit friends) felt like a stab in my heart. Now we are 7 years into marriage and I see everyday all I've given up to be with him and I realize, perhaps it wasn't worth it. There is no way to collect on his promises now that we have children. He can never commit to just my happiness for any amount of time. At this point I don't know what would make me happy. I just don't see my happiness as something I can achieve here.