and I am sweating a lot by now and thinking of leaning on the john door in the 5 SPOT
The speaker is sweating and thinking about the time he was leaning against the bathroom door in a nightclub called the 5 Spot.
The poem leads us to believe that his sweating is related to learning of Holiday's death, but you could read it another way: it's July, summer in New York City. Couldn't he just be sweating from the heat? In this poem, any hints of grief are masked in uncertainty.
The sweating detail is also significant because it makes the image of the nightclub more powerful. We don't know about you, but most of the music clubs we have been to have been hot, sweaty affairs.
The 5 Spot was a real club, and O'Hara saw Holiday perform there. He was sitting by the bathroom.
while she whispered a song along the keyboard to Mal Waldron and everyone and I stopped breathing
The poem has been very noisy so far, filled with the bustle and commotion of New York. But at the end things get quiet, as we strain to hear how Billie Holiday "whispered a song along the keyboard" to her pianist, Mal Waldron.
The performance is so subtle and mesmerizing that everyone in the club holds his breath, afraid to miss a single note. Or as the speaker dramatically puts it, "everyone and I stopped breathing."
The poem ends on this phrase, as if it, too, has "stopped breathing."
After hearing all about the trivialities of the speaker's day, we're left with a breathless memory of a great performer holding her audience captive.