Leaving apartment before end of contract?

My contract started on August 2022 and it will end at the end of July. In my current apartment, one of my flatmates assaulted me a few months ago. I reported the incident to the police and asked to either leave or have the person who assaulted me removed. However, they have not allowed me to leave and have not removed the person who assaulted me. I have found a room to rent starting March 1st, but they have told me that if I leave, they will charge me an additional 500 euros and keep my deposit. Is there any way I can prove to them that I can leave without hiring a lawyer? I am a student and cannot afford it. I can send you the contract I've signed.