Chat room guy?? whats happening here?

[me!]

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i met this guy in a chat room. I was just fooling around and then this guy sent me a private message. and i jokingly made a rather rough move by kinda insulting him. He felt humiliated by this and came after me and started saying negative things to me. Im a sensitive person so i sensed that he must be the same to act in such a way. Then later he admited that hes shy and sensitive. I felt so close to him because he was just like me.

Any way i could never consider him because of certain things he said (insulted me and said that hes not close to his family and etc) and im not looking for someone like my self because i know how sensitive people can be hehe.
My problem is this...recently when we were chatting he made a joke which i became offended about. It was a gender based joke which i didnt like. I felt like hes testing the sands so to speak before making any other sexual advances. And i told him off saying that what he said was stupid and i logged off from the chat room.
My problem now is i feel like i've broken up with someone even though i never loved him in the first place. i felt like we had so much in common in regard to our personalities but now its all ended because he made a stupid comment. So does that mean that he wasnt the person i thought him to be? i dont get it
Today he came in another name and started speaking to me and i recognized him and told him that i knew.
What is happening to me? why do i feel down because of this? is it my fault for believing we can be good friends or what?