What should I do to my best friend who hurt me badly?

I had bestfriend from online. Things were not going well (in his opinion) then with unknown reason he pushed me away. But then I found out, he still chat with other friend (my friend from real life). I felt betrayal and confused what makes him did that. He still read my blog regularly but refuse to chat with me. What should I do? I am angry and hate him but he ‘haunted’ me since my friend keep mention about him. FYI: we r pure friend