I wrote him what we said, he replied that it has nothing to do with T although T is a part of it of course.

(What a logic.)
Then we talked on the phone. He said he believes that a man and a woman cannot really be best friends, and that the man is only best friend if he wants more and doesn't get it.
He also said that
he would like to be with me now, and that T has what he doesn't have, and that annoys him because he wants to have me, not someone else.
He didn't put any blame on me, he said it's his problem and he will handle it alone. However, he was being emotionally very hard and closed off, like "I'm strong, I'll manage". Nothing wrong with being strong, but this being strong was directed against me in some way. He was distrustful and defensive but doing as if everything was fine. I even felt some resentment on his side, and a big distance. I tried to create closeness but failed.
At some point I asked him if he has some female friends, he said yes. I asked him if he wants to get into their pants, he said of course not, he's not in the slightest interested in them as sexual beings. So I asked why with me and T it's different and he said his lunch break is over and he has to go.
I'm feeling sad, I don't know why.
I don't mind him having a different opinion than mine about men-women interactions, but I do feel uncomfortable with him wanting to "have" me and seeing all guys as rivals, and going all defensive towards me. I don't know, I'm being confused. My alarm bells are ringing like crazy and my head says "Run! Run!"