Discuss the way Williams treats homophobia.

The crucial revelation in the play, made by Blanche to Mitch, is that Blanche had been married to a gay man. Blanche recounts her having told her husband, after discovering him together with another man, that she was "disgusted" by him. The "boy," as Blanche refers to him, then committed suicide.
Though Blanche's reaction is an instance of homophobia, it needs to be understood in the context of her having been in love with the man and then stunned by seeing that not only is he being unfaithful to her, but it's with another man. By the standards of the time (the 1940s), Blanche's attitude is not unusual. In fact, her regret over being responsible for the young man's death is one factor that sends her life into a downward spiral. A "conventionally" homophobic person would probably have reacted in a colder, harsher way to the entire situation.
Blanche states that she sensed there was something different about the young man before she married him but that she wanted to help him. It is arguably the general condemnation of gay people that was typical of the time that allows the situation to develop as it does between Blanche and the young man, with tragic results. For dealing in such a revelatory way with this subject, Williams, a gay man himself, was a pathbreaker in American literature.