In an emotional second day of testimony in his federal corruption trial, former Virginia governor Robert F. McDonnell portrayed in searing detail the slow collapse of his marriage from the couple’s days as young lovers in Germany to battling, estranged antagonists in the governor’s mansion.

The climax came as McDonnell (R) presented to jurors an e-mail he sent his wife in September 2011, in which he wrote he was “spiritually and emotionally exhausted” and begged her to help him save their marriage. Maureen McDonnell, he testified, did not respond.

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“I was heartbroken. I thought maybe this is the end of my marriage. Maybe we were done,” he said.

In laying bare the details of a failing marriage in hushed tones to a rapt courtroom, McDonnell hopes jurors will believe that his dealings with businessman Jonnie R. Williams Sr. were the machinations of an erratic, alienated first lady, crushed by the pressures of public life and possibly romantically attracted to Williams. In McDonnell’s telling, he was far more a bystander than a co-conspirator.

List of gifts given to the McDonnell family from Jonnie Williams.

That claim is central to both his and his wife’s defense against a 14-count indictment alleging that they conspired to lend the prestige of the governor’s office to Williams in exchange for $177,000 in gifts and loans from the businessman.

Throughout it all, Maureen McDonnell sat listening silently at her defense table, impassively watching.

McDonnell provided a litany of examples of his wife’s interactions with Williams that he insisted he did not know about at the time: He didn’t know the businessman spent $20,000 on clothes for his wife during a New York shopping spree in 2011. He didn’t know a $6,500 Rolex his wife gave him for Christmas that year was actually purchased by Williams. And he did not learn that Williams lent his wife $50,000 until a few weeks later, by which time it had been spent.

On the 19th day of his trial, McDonnell spent nearly six hours on the witness stand making what experts say is the pitch of his life. What he says — and how he says it — will determine in large part whether he and his wife go to federal prison, especially when it comes time for federal prosecutors to question him. That pivotal moment could begin tomorrow or perhaps early next week.

Under oath, McDonnell said he believed that his wife was getting a kind of emotional support from Williams that he wasn’t giving her himself, although he didn’t believe that the two had carried on a “physical affair.” It hurt him to learn that his wife had exchanged more than 1,000 texts and calls with Williams, “more than she talked to me,” he said.

Even now, McDonnell testified, their marriage is “basically on hold.” He said he has been living with his parish priest in the rectory of St. Patrick’s Catholic Church, having moved out of the family’s suburban Richmond home shortly before the trial began.

“I knew there was no way I could go home after a day in court and have to rehash the day’s events with my wife,” he said.

He began the day’s testimony by asserting, under questioning from defense attorney Henry “Hank” Asbill, that this was going to be tough. During his public career, McDonnell said, he had always tried to keep his family and his personal money matters private. His finances had been detailed in previous testimony; now he was ready to recount the most intimate details of his strained marriage.

“It’s going to be very, very difficult,” McDonnell said, his voice growing almost inaudible.

According to McDonnell, his relationship with Maureen began in 1973 when he was a Notre Dame undergraduate and they met through friends. She spurned his first few entreaties but eventually agreed to go out with him and, later, marry him.

The early years were like an “extended honeymoon,” he said. But things changed as the family grew, he said. The logistics of five children took the place of dates and dinner conversation. Maureen McDonnell seemed to become more harried, less happy.

The stresses, and the distance, grew as he rose in Virginia politics, McDonnell testified. His wife had been both excited and apprehensive about his ambitions. He described her as eager to see him succeed — and even to accomplish good things of her own as the wife of the state’s attorney general and then first lady — but also jealous of his time away and uneasy in the spotlight.

By the time they moved into the executive mansion, he said, the strains had nearly crippled the marriage. Maureen McDonnell was frequently anxious and distraught, battling with her staff and yelling at him.

During one bitter fight, he pressed her to use a check of about $25,000 she had received from her father’s estate to pay down their “pretty significant” credit-card bills. She wanted to buy stock for their children, and the argument ended with her throwing the check at him and telling him to “pay the bills.”

The emotional note he sent her in late 2011 didn’t seem to improve things. In the note, which the judge did not let him read aloud in its entirety, he told his wife that he loved her, that she was his “soulmate” and that he was “a sinner” trying to do better.

“But I am completely at a loss as to how to handle the fiery anger and hate from you that has become more and more frequent,” he wrote. “You told me again yesterday that you would wreck my things and how bad I am. It hurt me to my core.”

He testified he later learned that his wife had been in contact with Williams four times the day he sent the letter.

When Williams first sat down with the couple, shortly before McDonnell was inaugurated, the former governor said he liked the colorful businessman at once. “He was gregarious. He was funny. He was charming. In my mind, he was a Virginia businessman who had some ideas about creating jobs.”

And he was clearly rich. Williams bought a $5,000 bottle of cognac at that meeting, in New York, and immediately offered to buy Maureen McDonnell an expensive designer gown for the inauguration. McDonnell’s senior staff nixed the offer. McDonnell attributed Williams’s largesse — then and later, as it grew to ever more lavish gifts — simply to his great wealth.

“I knew Mr. Williams had the capacity,” he said in connection to Williams’s offer 17 months later to give one of the McDonnells’s daughters $15,000 to spend on her wedding. He said he considered the wedding offer more acceptable than the dress, he said, partly because the two families had known each other longer and it was a gift to his daughter.

McDonnell said ignorance more than greed explained his acceptance of some of Williams’s parade of gifts. He wasn’t aware, for example, of how much golf rounds could cost (one of the outings for McDonnell and his sons that Williams paid for ran to more than $1,000).

“I’ve never belonged to a country club in my life,” he said.

Although Virginia law requires the disclosure of gifts given to elected officials that cost more than $50, he did not disclose the golf rounds. He partially shifted blame to the businessman for that oversight, because Williams never submitted a form alerting his office to the value of the gift. But under additional questioning from his attorney, he admitted, “that’s my fault.”

McDonnell said he was also comfortable accepting a vacation at Williams’s lake house in July 2011. But he didn’t know that his wife had arranged for the businessman’s Ferrari to be taken to the Smith Mountain Lake house for his use and believed that he was merely doing Williams a favor when he drove it back to Richmond.

“I hadn’t driven in almost two years,” he said, explaining why he took the wheel. “At some point, I’m entitled to be normal.”

He said he had no advance notice of a $50,000 loan to Maureen McDonnell by Williams, insisting that the suggestion from Williams that he had told the governor about the check before giving it to his wife was “absolutely false.”

He said he was “astounded.” The couple did not need the money, and he had the family’s finances under control. But he also did not tell his wife to give the money back.

“I just needed to pick the battles with my wife on certain things very carefully,” he said.

He said he was not uncomfortable with the largesse because Williams never asked him for anything.

“I haven’t done anything for Jonnie Williams. He hasn’t asked me for anything,” McDonnell said, explaining his reasoning for not returning the $50,000 loan. “Star Scientific hasn’t asked me for anything.”

Laura Vozzella, Rachel Weiner and Fredrick Kunkle contributed to this report.