The woman told London's Southwark Crown Court that Mr Travis, now 68, put his hand up her skirt and touched her breast while they were alone at the opening of a hospital radio station in 1973.
The witness, who cannot be identified for legal reasons, said Mr Travis had a "haunting look" on his face as he touched her and she felt "frightened" and "ashamed" so avoided watching the former Top Of The Pops presenter on the TV again.
Breaking down in tears, she said her ordeal had an effect on her love life with her late husband, who would never know why.
"When he put his arms around me, I'd freeze," she said.
The woman, who said she was brought up a strict Catholic, said the incident left her too scared to go out on her own.
She said of Mr Travis: "He screwed a lot of my life up."
The former BBC presenter, who is on trial under his real name, David Patrick Griffin, denies 13 indecent assaults and one sexual assault, dating back to 1976.
Prosecutor Miranda Moore QC told jurors the woman's evidence did not relate to any specific charge against Mr Travis.
The trial continues.