What are my legal options if ex is falsely accusing me of strangulation?

My ex-girlfriend filed charges on me saying I strangled her, which is completely untrue. She filed them when she found out I was back with my ex before her. Now she is harassing me and my girlfriend. She is telling me that she’s tried to drop the charges, but then when she hears something about my girlfriend and I she tries pushing for more charges. She has also threatened my life and expressed concern about getting a psychological evaluation done because she knows she will not pass. Any advice?