Feeling heartbroken, lost and empty...?

Why do i feel like this? Someone your so close to and and you feel like they dont care anymore. I made some stupid mistakes in the past year and now that ive copped on and realise what ive done....i feel like ive lost him/her because of it. That person still talks to me but were not the same and i miss it so much! I'm aching inside. What do i do?