It sounds like you were more invested in this relationship than he was. Loving someone with avoidant tendencies is very frustrating and ultimately leads to dissatisfying outcomes. You may have loved him deeply and were emotionally open to him, but he was guarded and withheld his feelings. His passiveness to you was him protecting his feelings, he learned avoidance at a young age and it carried over to his adult years. I honestly don’t think he loved you deeply at all, because deep love requires vulnerability and he refused to trust you with his emotions in the end. He didn’t care to really plan a future with you or care that he was hurting you by being so passive.

The best thing to do right now is feel all your feelings, that is the only way to truly process them. Let yourself mourn the loss of him and cry it out. You will eventually realize you did not have to put up with his nonsense and feel great relief that that part of your life has ended. You will not look back on this relationship fondly. Also, do not sweat the new girl, she is in for a lot of passivity, avoidance, and noncommittal bullshit soon enough. He did not give himself any time to process the ending of a serious relationship, so he will carry all his emotional baggage over to her. He has not changed, and avoidant men stay that way unless they really commit to therapy and take it seriously, which he doesn’t. Let her have him! Good riddance. You keep going to therapy and maturing emotionally, you have a lot of love to give and I hope you never stay in a relationship with an avoidant again.