Greetings. First, on the custody issue, you are not likely to obtain primary custody when you already agreed to joint custody. My suggestion is that you focus on forcing him to follow the agreement.
Here is my suggestion:
Write him a letter/e-mail (keep a copy) and in the letter inform him that he has agreed to pay, it is a rightful debt, you are suffering an injury, etc. Give him a set amount of time to get the debt current and tell him that if it does not happen by a certain date, that you will file an action for breach of contract against him. Let him know that if he files for bankruptcy you plan to ask the court to treat the debts as non-dischargeable.
Talk to an attorney, and figure out if your agreement will allow you to recover attorney fees.
Hire the attorney to file a breach of contract action on your behalf in the event he does not continue to pay on the debts by the date you set.
My advice is that if he is paying something, that you try to work with him. Do not modify the agreement in any writing, but continue to remind him that he is not meeting his obligations. Best of luck.
Janet L. Fritts
Attorney with Rosen Divorce
4101 Lake Boone Trail, Suite 500
Raleigh, North Carolina 27607
The response posted above is based upon the limited factual information made available and is not intended as a full and complete response to the question. The only reliable manner to obtain complete and adequate legal advice is to consult with an attorney, fully explain your situation, and allow the attorney sufficient opportunity to research the applicable law and facts required to render an accurate opinion. The basic information provided above is intended as a public service but a full discussion with an attorney should be undertaken before taking any action.