'The benefit of Mr. Trump': Longtime fixer Cohen testifies in hush money trial. What you missed on Day 16.

Donald Trump’s longtime fixer and lawyer, Michael Cohen, testified Monday that he was acting at Trump's behest when he made hush money payments to Stormy Daniels before the 2016 presidential election.

For weeks in Manhattan criminal court in New York City, Trump's defense attorneys have sought to puncture Cohen’s credibility with the jury, and even witnesses have painted him as hot-headed, self-interested and untrustworthy.

“I didn’t know Michael to be an especially charitable person or selfless person,” said Hope Hicks, Trump’s former communications aide, when she was on the stand. Cohen’s former banker said he was assigned to him because of his “ability to handle individuals who are challenging.”

But on the stand for the first time, Cohen presented himself as cool-headed and recalled how he had worked at Trump’s behest to suppress stories that posed a threat, negotiating with tabloid publisher David Pecker and ultimately procuring $130,000 of his own money to pay off a porn star — with the promise of reimbursement.

“You’re a billionaire. Just pay it,’” Cohen said Trump’s friends told him. “And he expressed to me: ‘Just do it. Meet up with Allen Weisselberg and figure this whole thing out.’”

Cohen and prosecutors have made no secret that they have gone to lengths to prep him for his testimony — but the real test may come Tuesday, when cross-examination by Trump's lawyer is expected to begin.

But first, here is what you missed Monday:

Trump v. Cohen

Cohen's testimony had long been billed as the main event — a former Trump confidant who was closer to him than almost any other ally, having flipped — a term Trump often employs — and agreeing to testify against him.

The prosecution spent much of the run-up trying to bolster Cohen's credibility by using documents and the accounts of reluctant witnesses and some who remain in Trump's good graces as corroborators.

That was done to try to make Cohen sound more believable.

“What I was doing was at the direction of and for the benefit of Mr. Trump,” Cohen said on the stand. (Trump is charged with 34 counts of falsifying business records related to the payments Cohen paid. He has denied all charges.)Trump’s shoulders were slightly slumped, and his eyes remained closed as Cohen explained in grinding detail how he was working hand in glove with Pecker to “catch and kill” stories and testified about private conversations with Trump, including one Cohen recorded, which was played in court.

Cohen offers some sentiment about his time working for Trump

Cohen cut a slight figure as he arrived in the room. A court officer towered over him as he walked behind the defense table and to the stand. He appeared thinner, his hair gray and his voice growing stronger through the day.

Like those of other witnesses, Cohen’s early career blossomed after he began to work for Trump. He was working at a “sleepy” law firm before Trump enlisted him to do some work on a Chapter 11 reorganization of Trump Entertainment Resorts. When Cohen approached him about the bill for his services, Trump offered him a job, and he accepted. The bill was never paid.

Cohen said he enjoyed working with the “big family” at the Trump Organization. He felt a sense of obligation and sometimes lied for him, he said. “The only thing that was on my mind was to accomplish the task to make him happy,” he said.

Damage control

After he learned in early October 2016 that Stormy Daniels was looking to sell her story, Cohen said, he feared a “catastrophic” effect on Trump’s campaign.

The campaign was dealing with the fallout from the “Access Hollywood” tape and fearing mounting electoral consequences. It was the idea of Trump’s wife, Melania, to dismiss the recording as “locker room talk,” Cohen said Trump told him.

Cohen described escalating concern as a deal to suppress Daniels’ story began to fall apart.

Trump pushed Cohen, he testified, to strike a deal and then delay payment until after the election — arguing that win or lose, it wouldn't matter that the story came out afterward as long as she stayed silent through Election Day in hope of a payout.

“Because if I win it will have no relevance, and if I lose, I don’t really care,” Cohen said Trump told him.

Cohen makes the payment — and then is angry about his bonus

At the heart of Cohen's first day of testimony was a running theme —something the prosecutors had thus far failed to show — that Trump was personally aware of every step, in the payments to both Daniels and former Playboy Playmate Karen McDougal.

Cohen said he met with Weisselberg, the Trump Organization chief financial officer, to figure out ways they might be able to Daniels or repay the National Enquirer without having Trump's fingerprints on the payment. Weisselberg floated different mechanisms to fund the payment, such as a golf membership, but he said they needed to separate the payment from the Trump name and so devised a plan for Cohen to form an outside shell company and use his own money to pay, Cohen said.

Cohen testified that months later, when he received his annual bonus — a check that was consistently large over the years, he was shocked to find it was two-thirds lower than in previous years.

Add that to having already paid out of his own pocket to silence Daniels but not yet having been reimbursed, and Cohen said he was irate.

“I was truly insulted, personally hurt," he testified. “After all that I had gone through in terms of the campaigning, as well as things at the Trump Organization, laying out $130,000 on his behalf to protect him — that the gratitude shown back to me was to cut the bonus by two-thirds.

“I actually had to do a double take.”

Trump wasn't worried about upsetting wife

Trying to anticipate an argument the defense has appeared to invoke, Cohen was asked about whether Melania Trump was the motivation for the hush money payments.

Cohen testified he had asked Trump about her, saying, “How are things going to go upstairs?”

“Don’t worry,” Trump responded. “How long do you think I’ll be on the market for? Not long.”

Anticipation of women's stories

Cohen recalled before the jury how Trump told him that once he launched his campaign, he risked women coming out of the woodwork to sell stories about him.

“You know when this comes out,” Trump told him about his presidential announcement, “there are going to be a lot of women coming forward,” Cohen said.

That's what led to the 2015 Trump Tower meeting with Pecker, Cohen said — an agreement that the Enquirer could make Trump look good while he ran for president.

"If we can place positive stories about Mr. Trump, that would be beneficial," Cohen testified. "That if we could place negative stories about some of the other candidates, that would also be beneficial."

This article was originally published on NBCNews.com