friend borrowed money over time and says he will pay me back but never does.

Over the past year i let a friend borrow money to pay bills, buy food, gas,clothes rent, babysitting etc. He was not working over the past year neither was his wife. so i was willing to help them out. everytime i lent them money i wrote it down and kept track. When i asked for the money he never paid me anything or even attempted to. he now owes me 6,500. he has now ruined me credit and i lost my job cause of him. I kept all the messages where he admits to payin me back for the money. They both have good jobs but wont pay me anything. what should i do?