Payment of support is a separate issue from Termination of Parental Rights. You can TPR him and still collect. That said, you might use non-payment (and most certainly abandonment) as evidence for a TPR.
Frankly, I would not recommend it. The burden is high and outside of his agreement you take a chances at failure. Most importantly, he would get notice of your action and might be motivated to get involved as is his right.
You should consult with an attorney about the specifics,...
If you have some documentation or evidence about the loan, you might be able to get that back. That is potentially a complex off the contract remedy. Seek a specific consultation with an attorney for this.
MA does not recognize common law marriage.
You may be able to recover from other sources besides her insurance company; her directly, your insurance company or maybe others depending on fact and circumstances. You also may be able to negotiate those bills lower.
This is why is it important to retain an attorney knowledgable in this kind of work.
Statutes of limitation for personal injury is 3 years. If the injury was to a child there might be ways to argue more. Available damages are for medical bills, out-of pockets costs and pain and suffering.
You should talk to an attorney about it, especially as most should take this kind of case without a retainer and on contingency.
You file a motion for contempt with sanctions. As part of that remedy ask for attorneys fees and interest from the judgment. You should retain an attorney, not just for results but because of attorneys fees.
You may have a consumer protection action.
You can report them to the Better Business Bureau, NH Consumer Protection.
If your damages are "mild" then you really do not have sufficient damages to make this suitable for a direct personal injury action, unless you are part of a class action.
Yep, it's crossing the "icky" line. It was enough for DCF in CT to make a case in Juvenile Court, with a past client of mine.
A restraining order would work. Along with a no contact order. Even easier you can and should not give him the child until he gets some help to understand why that was a problem.