What does Daisy learn of Gatsby that makes her draw "further and further into herself" and that took "whatever courage she had had"?

Tom exposes Gatsby's questionable dealings with Walter Chase and Meyer Wolfsheim. Daisy is alarmed and frightened by Tom's revelations.

It passed, and he began to talk excitedly to Daisy, denying everything, defending his name against accusations that had not been made. But with every word she was drawing further and further into herself, so he gave that up, and only the dead dream fought on as the afternoon slipped away, trying to touch what was no longer tangible, struggling unhappily, undespairingly, toward that lost voice across the room.

The voice begged again to go.

“please, Tom! I can’t stand this any more.”

Her frightened eyes told that whatever intentions, whatever courage, she had had, were definitely gone.