Really need some advice about my marriage, and my life.?

I've been married for almost 2 years, and I have two children. We've been in poverty since right after we got married, and I feel that I could give my children a better life if I separated from my husband. He's a great guy and a great father, but I don't believe he's grown up enough to be a provider for our family. I've given him chance after chance, to prove to me that he can get and keep a steady job, and provide for our family. He says that's what he wants to do. But things have gone unchanged. What would you do in my situation? Would you sit back and keep waiting and giving him chances to be the man that your family needs? Or would you just take your two kids, and do it by yourself? I do have family to help. I need honest opinions here, nothing mean please. I know it will hurt him if I end things, but I've tried so hard to get him to realize how important it is for him to have some ambition. I've given him ultimatums but it seems like he either thinks he can just float by on the welfare system, or just doesn't know what it means to have ambition? Help :(