Fascinating thread, I have read every post and now I will post my own opionion. I have always believed that, from everything I read that he was gay, in the sense of being attracted too, and having affairs with men. But he was bisexual too, as he was married, had one child, and more than likely had affairs with women too. I think he liked to experment sexually. That was common in his day and age. Edna St. Vicent Millay, the 2oth Century American poet, was oriented towards men, but had flings with women too, when she was young, in her college days. No one has ever called her lesbian. The correct term is bisexual, at least to me. I think Felix was pretty serious about being gay though. As for being closeted, well I think many in Russian society knew of his inclinations.
He was techincally a murderer, because he killed someone. The murder of Raspution needed to be accomplished, no doubt, if not in the way it was done. I think whether he would have gotten away with it depends on what society you are talking about, and in what sense. He might of, but is useless to speculate whether he would have gotten away with it in modern times.
I think people back then did know what streight and gay was, if not in our modern terms. I doubt they knew what bisexual was. I Judge this is the correct term to define Felix. I don't think we should judge people in history unless they were really bad, like Rasputin, or Hitler, etc. I think Felix was a huge character, someone who can interest us today, and be a relevant topic of debate. Whether good, or bad I don't know. The child of money, and blue blood, blessed with a fascinating personality and great looks, I don't think it is our place to judge him.