There are several issues here that need to be addressed immediately.
1. You state he has not paid child support since April of 2009. If there is a court order ordering him to pay a certain amount every single month, you need to file for contempt of court. He cannot simply stop paying child support.
2. You also need to modify the parenting plan and potentially the child support order. It does not sound as though the situation at the father's house is safe or appropriate for the kids. Further, if he is not exercising his court ordered visitation, you may be entitled to an increase in child support.
You really need to speak with an experienced family law attorney in your area as soon as possible. You need to bring whatever court orders you have to the meeting. The lawyer can help you decide how to proceed.
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