How to control my anger for BIL &SIL who borrowed money from my DH and have not payed us back?

About a year ago my DH loaned his brother and our SIL $2000. They needed the money to move out of state. They were kicked out of thier previous rental home for reasons unknown but I am sure it was financial. MY BIL called and begged for the money and needed the money ASAP. My DH felt obligated to help his only sibling however like me we knew that my BIL & SIL are not responsible when it comes to anything especially money. MY BIL was desperate and so my DH decided to take a chance and "loan' them the money with the understanding that they would pay it back in monthly installments. We had to take the money to loan them out out our bank and explained to him that after 6 months there would be interest involved. He agreed and advised us that he had a good job waiting for him in his new city as well as one for his wife/SIL. Well of course they moved and we never heard from them. We did locate them eventyally and they ignored our emails, calls regarding the payback money. We eventually got a check for $50 which bounced! After another 5 mths of asking for payment we got a money order for $25 only with a note saying that they would be paying us $150 monthly...which was fine with us. Then again nothing from them. My husband send another email/letter with the breakdown of what they owe etc... We just got another money order for $15 only and no note. I understand that money may be tight but their lack of communication is what bothers us the most. What would you do? I know we should probably just write it off but I can't take their facebook updates of what they are up to with going out, buying iphones, trying to concieve etc. We are their family and I am sick of being treated like the enemy from them. advice?