Can I sue a sibling over an unpaid loan?

About a year ago, my sister called me and said she needed to leave her husband, that he was beating her and the kids. She asked me if she could borrow money to get away from him and rent an apartment and so forth. I really could not afford to help her being that I am a single parent and struggle myself, but because the situation was so dire and she was being physically harmed, I went ahead and sent her two western unions, one for 1,000$ and another for 2,300$. That was EVERYTHING that I had in my savings and I had been saving up to pay the property taxes on my home and car and so forth in April this year. Now, it's coming up due and she refuses to repay the loans, despite the fact that I might lose my house if I can't pay the damn taxes on it because I loaned her the money. Is there ANY way to sue her and get the money back within a 1 month period of time? How would I go about doing that? Thanks!