Did your divorce decree have a property settlement attached? It should have spelled out who was responsible for paying the loan you had together.
As far as getting Restraining Order, make sure you get an actual Order of Protection. They are issued by the Criminal Courts and enforceable by police. Restraining Orders are issued in Civil Court and the Judge who issued it must issue a warrant for the person that violated it. At least this is how it works here.
In many cases,here, Judges are reluctant to issue mutual Protection Orders. I guess there thinking is "why would a person who has a PO against some one want to harrass that person" They don't see the real world of "I got a PO, I can F*** with you all I want, and you can't do do chit about it"
I would have your new GF get a PO and one for yourself if they will give you one. Get a voice activated tape recorder and document EVERYTHING.