The best thing you can do is to give her space and don’t pressure her to understand what you feel. Apologize for your mistake and let her decide if she can forgive you. She needs to undergo to healing process alone.
Let him process everything and give him some space. for now, just focus on yourself and wait if he still care for you he will reach out and come back to you.
Just take it slow because I think he’s still interested to you since he reached out and apologized but make sure he will choose you because he love you and he totally moved on with his ex.
For me, give him space for a while and don’t chase him. If he love you, he will make effort for you and don’t let you go. If he allow you to leave him, meaning he doesn’t care about you.
It’s not about winter break. It’s all about the true feelings of the guy towards you. His feelings probably changed with or without reason. Try to give him space and let him miss you for a while. If he doesn’t miss you, it means he doesn’t care about you.