the person I hate the most

So I had a best friend for like two years and out of the blue they just started to ignore me. I tried to talk to them and they fully reflected and didn't apologize when I apologized TWICE to them. we stopped being friends which sucked but it got worse bc they're in the same college course as me.... like the fuck? 

I found out from a different friend that they've been talking shit about me and my mate to their friends and I just can't even deal with it anymore.