At the end of week three, he entered the witness stand.
When being questioned by his barrister, Kieran Vaughan KC, he was defiant in his denials.
Of the rape allegation by Complainant B, he said: “It just didn’t happen. I am absolutely crystal clear about that.
“It is just simply not true.”
At one point, he choked back tears.
There was also discomfort, as he told the court about the affair in 2008.
It had been with a divorced woman in London, he told the jury, and it had caused his wife “hurt and pain”.
He said he would regret it until his dying day, as he regretted other things he had done.
But he had not, he insisted, committed the offences he was charged with.
At one point he told his barrister: “We are all sinners Mr Vaughan, I am a sinner.
“Every day we ask God for forgiveness.”
When prosecuting barrister Rosemary Walsh KC got to her feet, it was time for Donaldson to face tougher lines of questioning.
For much of the first session of his cross-examination, he seemed confident, composed and assured.
But, when court returned on Friday for his second day on the stand, Donaldson’s composure began to crack.
Walsh tried to unravel his defence, at one stage focusing heavily on the meeting with Complainant B in the late 1990s.
He said he did not accept the meeting to “nip it in the bud”; denied taking control as soon as he walked in the room; and told Walsh he did not remember tears from Complainant B when it ended
But, at times, it seemed he was struggling to produce coherent answers.
His responses became longer and drifted off topic.
At times he talked over Walsh and, on a couple of occasions, she asked him not to answer a question that she had not yet asked him.
By the end of his second day, he had been questioned on the stand for almost 10 hours.
Walsh put it to him that a pattern had emerged down the years – not of sexual abuse but of seeking forgiveness by using his faith and the faith of his victims.
She said one example was the letter to Complainant A in 2020.
Donaldson replied: “When you have wronged someone, what is wrong with seeking forgiveness?”
But he maintained the letter had nothing to do with the allegations.
At the end of her cross-examination, Walsh returned to the issue of lies.
“The only person telling lies is you,” she told him.
“You were sinful and deceitful.”
By day 20 of the trial, and after 10 hours deliberating, the jury had a unanimous verdict.
In the end, they agreed with Rosemary Walsh.
The only person telling lies was the defendant.
Judge Paul Ramsey remanded him in custody and told him he was facing a lengthy sentence.
Donaldson showed no emotion as he was led out of the dock and into a prison van.
But four weeks after his confident walk into court, one of Northern Ireland’s most high-profile politicians was left to face up to his fate, as a convicted child sex abuser, alone.