She’s 21 and you’re 22. You both know how to be civil in the same room. Sometimes that takes the form of ignoring the other person after acknowledging their presence (eye contact, quick wave, etc.); if she wants you to change to have a chance, then change and give her space while doing it. It’s up to her, and she doesn’t expect you to change overnight. Not even in a month it sounds like. So either change and try, or don’t and let her go. Relationships end and so do friendships. It’s not your job to try and give her comfort as a friend because right now you ruined the relationship. She’s trying to recover, and you’re not going to be able to help at the moment.