If you can't let go, you should tell him how you feel.

He ask because he cares. You do not have to be so mean to yourself. If there is no way to be with him again why keep him so close to you? Just shut him out of your life. It will be easier than watch him enjoying with another person.

Maybe he is pretending to get along with the new girl. Don't hurt each other in the name of love. If you miss him let him know. I would tell him it is the hardest thing to be so close to him but not with him. I would rather heal my wound alone. Please do not watch me drown in my own tears.