Can I sue my roommates for breaking a lease and reimbursement of deposit, they were supposed to pay back?

We traveled out of state to work in Nebraska. I had them sign papers, that stated they would pay me for the deposit I put down for all of us. When approached about the deposit, they got angry. So, I put my thirty day notice with the landlord. Now, they are moving out when I do, costing me their deposit owed to me. What are my courses of action?