I live in the same hotel with my ex and I find it difficult not to want to go to his room even when I know he is avoiding me. What should I do?

You should not go to his room. You can try living in a different hotel in order to feel less like going to his room. Out of sight, out of mind. You can also try operant conditioning. Every time you think of going to his room, you try pinching yourself or doing something else that's painful. Eventually, thinking of going to his room will be associated with pain, and you will automatically stop thinking of it. Another thing you can do is to go to his room, just to get it off your chest. However, you can act terribly and cruelly so your ex will treat you with reciprocal cruelty, so that when you think of him you will associate him with cruelty.