I can't move on, because I can't understand - how can he do this to me?
What Guys Said 1
It seems like he has a two-fold approach to addressing the breakup on his part: 1) he is using a "no contact" approach, possibly to help him move forward from you; and 2) this new girl sounds like a rebound with how quickly she entered the picture.
Without hearing from him, I can only theorize about his reasons. As for the new girlfriend, maybe they're together because he was cheating on you with her, and the last argument was when he decided to cut the cord? Or maybe she's just a rebound / flavor-of-the-week since he doesn't want to be alone, especially not at a public, social function.
If you haven't done it already, I think your best option is to work on yourself and to try to move forward from the relationship. Since communication is a two-way street, and he refuses to communicate, it seems like getting a solid answer or any closure will be impossible. I'm also certain that the approach of making out with the new girl, knowing that you were there watching, was very deliberate and was probably and attempt to make you jealous or get you riled up, which it seems like it has (understandably).
Fight fire with fire. Don't fall into his game. You calling, texting, asking his friends about him, etc. is stroking his ego in a huge way, because it's a sign of power that he can wield over you. And the new girl? Probably a rebound just to get you upset, because it's another power he can wield over you.
What Girls Said 1
It's super hard, you were together for a really long time, so it'll be hard for both of you to move on but it's possible, though it may take a super long time. He might appear to have moved on quicker than you but it's usually just a mask that guys use to protect themselves. My ex was very cold and cruel with me although we had a lovely relationship and I was always good to him and him to me. Guys just go like that for some reason. You will always have his heart and he could never forget you. You've taken a considerable chunk of his life, almost a decade. He may even come back as you have so much together. You have to focus on yourself until he sees his error. You might not ever get closure so try not to hold onto it, otherwise you'll definitely not move forward.
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