Im in roomate hell! what can I do?

My old roommate and I moved into another house, where I put down the bulk of the deposit. Just recently she decided without my permission, or the owners,to sublet one of the rooms. The woman she chose is an ex druggy drunk whos had no less than 30 men through the house in the last 2 months. My old roomie has fallen into that lifestyle as well. SO heres my dilemma. Ive talked to my roommate and told her I want her out, Ive also asked the girl to leave. Ive told the owner that my roommate has an unauthorized subleter, all he cares about is the rent is getting paid. So what can I do to get her out?.... The owner told me to take her to court to get her out. She has this "month to month contract" with my roommate so the Sheriffs wont do anything. Im $2600 in on the deposit and I have children in the house . We have a year lease, I'll lose my deposit if I leave early. I cant afford to leave and lose those funds.What can I do?