Zeta-Jones read excerpts from letters Wednesday during a preliminary hearing to determine if Dawnette R. Knight, 32, should stand trial on 25 felony charges of stalking and making criminal threats, the Los Angeles Times reported Thursday.
"I started to shake and sweat. I felt like I was about to faint. I had a tingling sensation in my arms, a burning sensation at the roof of my mouth," Zeta-Jones said.
Authorities allege Knight was infatuated with Zeta-Jones' husband, Michael Douglas.
Douglas testified the letters made his wife hysterical and indicated intimate knowledge of the couple's travels and homes.
"She felt she was a marked person. She couldn't figure out how they knew where she was," Douglas said.
The hearing was scheduled to continue Thursday.
Notable deaths of 2014 [PHOTOS]
Polly Bergen, Emmy Award-winning actress, dies