During the trial, Mr. McDonnell lamented a life of fights over credit card debt and stock purchases gone south as he watched his wife become more and more enamored of Mr. Williams, who showered the McDonnells with gifts the former governor repeatedly claimed not to know the value of.

The prosecution brooked no such arguments, and pressed Mr. McDonnell about fancy trips taken at Mr. Williams’ expense and a $20,000 shopping spree in New York for Ms. McDonnell, paid for by Mr. Williams. Mr. McDonnell testified that he had no idea that the spree was so expensive and noted that he had shunned an offer from Mr. Williams to purchase his wife an Oscar de la Renta gown for the inaugural balls, declaring it inappropriate.

Mr. McDonnell, who was governor from 2010-14, spoke of his wife time and time again throughout the trial, even reading from an email he wrote her lamenting the state of their life. “I am spiritually and mentally exhausted from being yelled at,” he wrote. “I don’t think you realize how you are affecting me and sometimes others with your tongue.”

Further, he detailed other fears about her abuse of her first lady role, saying that during his campaign for attorney general before he was governor, his political staff told him that his wife had used a campaign contact list to market her Nu Skin vitamin and cosmetic product line, a move that he called “completely inappropriate” and added that he was “very upset.”

The issue became significant because Mr. Williams tried to promote his nutritional supplement firm, Star Scientific, to parts of the Virginia government.

Mr. McDonnell’s attempt to shift blame to his wife did not sway the jury and was noted by the judge at his sentencing. Judge Spencer, in effect presaging his sentence for Ms. McDonnell, told the former governor, “While Mrs. McDonnell may have allowed the serpent into the mansion, the governor knowingly let him into his personal and business affairs.”

Some members of Ms. McDonnell’s staff also testified that she was difficult and even abusive as her marriage unraveled. At her sentencing, however, witnesses for the defense offered a more nuanced picture of Ms. McDonnell, painting her as a besieged housewife who had neither the fortitude nor background for the task of first lady. According to The Associated Press, Rachel McDonnell, one of the couple’s five children, said the scandal surrounding her parents had driven her family apart, and that her mother felt “very alone.”