Giving him the silent treatment is not the best way to handle this situation.
He was being honest with you. You should have asked him where he sees himself with you, in 6 months, or in two years, and see what he says.
I think a lot of people, myself included, still feel a certain type of love for people they’ve had relationships with in the past, but that does not mean that they still want that relationship with them anymore, nor do they pine away for that person.
It should become fairly apparent by what this fellow says and does, as to how he feels about you, or if he really is still “truly in love with his former girlfriend” and can’t get over her.
It’s OK to have fond, even loving, feelings for a person, in which that relationship is completely over.
My best friend still “loves” her highnschool boyfriend from 20 years ago, even though she was married for 10 years, and had a long term relationship after her marriage broke up. She is very good friends with the high school boyfriend and his wife, but she doesn’t harbor romantic love feelings for him, nor him toward her.
So you should talk to your boyfriend, and see how he really feels, and what kind of relationship he envisions with you.