Was wondering why you asked me about this situation directly.
First question, did you get the response from the parents yet?
It is not all your fault. Everybody do make their own mistakes and learn from it. You thought you guys will be together, but with the stance of unpredictable life events, it is not your fault.
This person owe you some moolah, so thus it is his responsiblity to pay you back. Maybe he is hoping to see if you forgot if he cut his ties off with you. But, it is quite impossible since it is hard to forgot the amount of $1000. Calling his parents is a good step once you used to have good relations with them in the past. I do recall a friend being stuck in this similar situation - and she decided to call her ex's folks to ask about the $3000 I.O.U - and, didn't work out - then called again and sayin that she will have a lawyer to be involved in this matter - and the folks paid her $3000. She lied about the lawyer. Such a risk - but she made it.
For you - wait to hear from his parents and see what they have to say. If it is not sucessful, let's figure a plan B. I think you had to step into their lives til you get $1000 back since it is under your name.
At least - you should be grateful that you are no longer being with him to see how he is not able to arrange his life priorities especially he is in his late 30s! Older people should be wiser, but guess not! 
He broke his promise and it is not your fault, baby.
That's all I can account for - if you tell me more - and see how new events of this situation arise - let me know
