The mother of Pete Hegseth, President-elect Donald J. Trump’s pick for secretary of defense, wrote him an email in 2018 saying he had routinely mistreated women for years and displayed a lack of character.

“On behalf of all the women (and I know it’s many) you have abused in some way, I say … get some help and take an honest look at yourself,” Penelope Hegseth wrote, stating that she still loved him.

She also wrote: “I have no respect for any man that belittles, lies, cheats, sleeps around and uses women for his own power and ego. You are that man (and have been for years) and as your mother, it pains me and embarrasses me to say that, but it is the sad, sad truth.”

Mrs. Hegseth, in a phone interview with The New York Times on Friday, said that she had sent her son an immediate follow-up email at the time apologizing for what she had written. She said she had fired off the original email “in anger, with emotion” at a time when he and his wife were going through a very difficult divorce.

In the interview, she defended her son and disavowed the sentiments she had expressed in the initial email about his character and treatment of women. “It is not true. It has never been true,” she said. She added: “I know my son. He is a good father, husband.” She said that publishing the contents of the first email was “disgusting.”

Questions about Mr. Hegseth’s treatment of women have emerged in the weeks since Mr. Trump chose him, a veteran of the Iraq and Afghanistan wars, to lead the Pentagon. The issue is expected to be a subject of scrutiny during Senate confirmation hearings.