What did I do to change him so much?

Oka, so about 2 months ago I broke up with my boyfriend, which was a HUGE mistake. He's always been really popular & outgoing, but when we broke up he changed. A LOT. He started not talking to anyone, started getting in trouble, etc. I think about that boy every single day. I love him SO much. When we broke up I got real depressed and cut myself, which was a big mistake. But I poured my heart out to him, told him how I made a mistake, how i still loved him, how I would do anything to have him back. And all he told his bestfriend was, 'I don't look at her the way I used to." What does this mean? I want the old Nic back! Please help.