What are Jordan's and the Buchanans' reactions to Myrtle's death in The Great Gatsby?
At first, as Tom stands over Myrtle's dead body, he is "motionless," and he seems to be in shock. After all, Myrtle had seemed so vital, so very alive when she was living, and her death is a rather gruesome one. When he hears George Wilson say that he knows exactly what kind of car it was that hit Myrtle, Nick says,
I saw the wad of muscle back of his shoulder tighten under his coat. He walked quickly over to Wilson and, standing in front of him, seized him firmly by the upper arms.
Tom orders Wilson to pull it together, and then he tries to quietly explain that the car he was driving earlier, the car that killed Myrtle, was not his car and that he'd only just arrived at the scene. He also tells Wilson that he had just been bringing him his little blue coupe that he'd been promising Wilson for months: a lie. Once he is confident that he is no longer under any suspicion, he whispers to Nick, "'Let's get out.'" On their way home, Tom "sob[s]" and "tears were overflowing down his face." He believes Gatsby killed Myrtle.
When they reach the Buchanans' house, Tom offers to call Nick a taxi, and Nick says he'll wait outside. Then Jordan puts her hand on Nick's arm and asks, "'Won't you come in, Nick?'" as though she wants to continue the evening as though a woman hasn't just been killed. She laments the loss of the night, saying, "'It's only half-past nine,'" but Nick suddenly finds he cannot stand to be with any of them right now, including her. "She must have seen something of this in [his] expression, for she turned abruptly away and ran up the porch steps into the house." She might be cold and callous, but she's also quite proud.
Of Daisy's response to hitting Myrtle with the car, Gatsby tells Nick,
'Daisy stepped on it. I tried to make her stop, but she couldn't, so I pulled on the emergency brake. Then she fell over into my lap and I drove on.'
It's telling that Daisy's first response is not to stop and check on the well-being of the woman she hit. Instead, her first impulse seems to be to get away as quickly as possible. The fact that she cries seems to have more to do with her own feelings of upset, rather than anything like sorrow for the woman she killed; this is corroborated by what Nick sees through the window of the Buchanans' home: Tom and Daisy sitting and talking and eating, appearing as though they are "conspiring together" -- Daisy isn't crying now.
Fitzgerald offers Tom's reaction first in Chapter 7. When Tom hears from the policeman that Myrtle is dead, he is dazed and can repeat only what the police officer said. However, just seconds later when an eye witness states that Myrtle was hit by a yellow car, Tom's reaction switches to anger and self-preservation. He immediately approaches the grieving George and explains that the yellow car he was driving earlier is not his. As Tom drives away from the scene, he does cry and assumes that Gatsby hit Myrtle without even stopping.
Daisy: The readers only knows Daisy's reaction from what Gatsby relates to Nick. Gatsby asks Nick if Myrtle was killed, and when Nick responds that she was, Gatsby states,
"I thought so; I told Daisy I thought so. It's better that the shock should come all at once" (144).
After hitting Daisy hits Myrtle, she cannot drive, and Gatsby takes over to drive her home. So, Daisy is obviously horrified by what she did but only briefly. For, that very night she sits with Tom, and they seem to agree how to handle the situation without either of them being implicated or affected by her action.
Jordan: Jordan has no reaction to Myrtle's death. It seems like just another event in her party lifestyle. When Nick, Jordan, and Tom reach the Buchanan home, Jordan waits with Nick, doesn't mention the accident, and becomes sulky when Nick doesn't want to do anything with her. She thinks the night is still young, and has no concern about the grieving George Wilson, his dead wife, or Gatsby.