Welcome to PC. You do have some challenges before you. Just the relationship alone would be challenging, but the needs of your children makes things worse. I would consult a professional counselor that specializes in these areas.
You might want to check the abuse forumSurvivors of Abuse - Forums at Psych Central
The challenge is to determine if the relationship is manageable for the sake of reaching a stable place for the children. If not designing a safety net might require a social worker to help define and establish the resources so you could continue to support your children.