California does not have/recognize common law marriages but the children are a concern and both of you must support them and come to a legal agreement (he has to prove he's the children's father first), as if you were married. I would find a lawyer and discuss your situation and then think about whether I wanted to mess with getting back together with him or go forward with making my own plans.

http://attorney.sandiegocafamilylawf...FeVx5QodM39c0g