How do I get a loan paid back.

I laon $1,100 to my brother in law due to a legal problem he had . I lost my job a month after I have ask for him to pay me back and he won't but will spend $200-$300 on his new girlfriend and said he doesn't have the money to pay me back . I have a 6 month old and one on the way when ever I ask for just 50 every two weeks he say he can only give me 20 $ loan . he doesn't pay bills we live in a house together and split a $400 rent in 3 because he won't let his girl pay rent and he won't pay more that $120 for water and light bill he makes $500 a weeks and buys clothes $120 and up twice a month its already been 4 months and not even a dollar has he paid