<human>: Summarize the given text in a few sentences.

So at the beginning of the year I started working with this guy. He seemed really interested in getting to know me and we became VERY fast friends. He was always very complimentary and listened to what I had to say and made me feel validated. When he broke up with his girlfriend, he came to me and I helped him through the breakup. At one point I had feelings for him but by then he had gotten back together with his girlfriend, so I didn't tell him. About three months ago, he changed the way he interacted with me. He stopped seeming interested in me and started saying things that were actually quite cruel. I went from feeling very safe with him to wanting to avoid him. I still have feelings for him, but don't want to as I know being around him will just cause me to feel inadequate, pathetic, and boring. 

Recently somebody suggested to me that he seems like a sociopath and I looked up the characteristics online and he has all of them. Super charismatic, very intelligent, very manipulative. He initially seemed to really care about my feelings but recently says things he knows upset me and when I call him out on it he says he does it because the way I react amuses him. Not long ago he did something that really upset me and when I told him he said something along the lines of 'that's your problem'. I confronted him and he eventually apologized, but only after I backed him into a logic corner. He didn't care how he'd made me feel. 

My question is...how do I go forward? We have to work together - we sit opposite from each other. And since I'm not good at making friends, he really is my entire social circle. I've got this warped feeling that I actually deserve to be treated the way he's treating me. He made me feel special and it's SO hard to let go of that. Yes he seems like a huge dick when I write this, and I understand how dumb it seems for me to still like him after all this bullshit, but he can also be a great person. I feel like it's my fault he's not being that great person to me anymore.
<bot>: Is my friend a sociopath, and if so, how do I stop myself from feeling that I just need to 'be better' and then he'll want to be friends again.