Why Swann is obsessed with Odette's lesbian relationships in Proust's Swann's Way

Not only does Swann become obsessively and irrationally jealous about and suspicious of Odette, in Proust's "Swann's Way," but toward the end of the Swann in Love part, a novel unto itself, he becomes tormented by the idea that Odette is bisexual, or at the least that she has had several affairs or relationships with women. In fact, he begins hounding her with questions about her attraction to women, and she lets slip a sort-of admission - but why does this point disturb Swann so much? Why does he keep picking at this particular wound to his ego? In some ways, you'd think he would be indifferent to her relations with women - the real threat to his ego would be if she threw him over for other men (he of course has no sense of remorse about his own ongoing relations with other women while he was pursuing Odette). I think this has something to do with the relations between Swann and the narrator, Marcel, as well as with Proust's own homosexuality. Part of the significance of the Swann in Love section is the way in which his obsessive possiveness then sense of loss and betrayal foreshadows Marcel's jealousy and tortured relationship with Gilbert (Swann's daughter) in the later volumes - but as is widely known, Proust was homosexual and Gilbert is a stand-in for the male lovers of his life. There's a lot of homoeroticism in Search of Lost Time, but always (I think) portrayed a shameful perversion. In a way, by confining homoeroticism to the minor characters and by allowing Swann to obsess about it and to express his disgust is a way by which Proust protects his own identity and builds a protective shield between Marcel the narrator and Proust the author.