A would-be suicide bomber accused of plotting an attack ahead of the 10th anniversary of 7/7 wrote that he was prepared to throw his life away because he could not bear to be parted from his "beloved" secret wife, a court heard.
Mohammed Rehman, 25, allegedly amassed deadly chemicals to make explosives at his home in Reading and asked Twitter followers for advice on which target to choose - Westfield shopping Centre or London Underground.
He is on trial at the Old Bailey alongside his wife Sana Ahmed Khan, 24, who allegedly helped him buy the ingredients for a bomb on eBay.
The couple kept their Islamic wedding from aspiring teacher Khan's well-to-do parents because they did not consider the drug-taking, divorced Rehman to be a suitable husband, the trial heard.
According to Rehman, events then "snowballed" and led to an "avalanche" in May when the couple were arrested and charged with preparing a terror attack.
In June, he wrote an anguished letter to his mother-in-law Saleen Ahmed Khan from Belmarsh prison begging forgiveness and explaining his predicament.
It was produced as evidence in the couple's trial as Mrs Khan was being cross examined by her daughter's legal team.
He wrote: "In order for you to understand this situation, I'd like to take you back to 2006, where I met the best thing that ever happened to me - a precious diamond of a woman - your beautiful daughter Sohni.
"The minute I laid eyes on her, there was nothing more that I could desire from life than to be with her forever. I did everything that I possibly could, even from without my capabilities, to facilitate a way for us to be together.
"But just when life couldn't seem to get any better, it was only the beginning of a series of obstacles between her and I, that grew greater with time - like the 'snowball effect' - resulting in this avalanche you see before you today."
He went on: "What I would like to point out is the fact that you, her parents, had already made your minds up about me, not allowing a chance for us to meet, that perhaps you could make a genuine decision regarding my suitability for Sohni.
"You had your reasons to despise me without knowing me, but I dared not challenge them. Thus I was prepared to throw my life away because a life without Sohni was not one that I had planned."
Rehman told Mrs Khan that her daughter had been "dragged into this with me" but was "completely innocent" and had been "undermined" by their association.
He added: "Had I wished to take your daughter away from you, I would have ran (sic) away with her, but I'm not one to take a family apart.
"I wish there was a way for me to compensate you for the sufferings that I have caused, but since there isn't I figured writing to you is the least I could do, as I can only imagine what you're going through right now.
"I'm truly and deeply sorry for everything and I'm also really sorry if this letter only adds to your pain. But if it makes you feel any better I have never been in as much pain as I am in today.
"They could give me a life sentence and I couldn't care less, but they've taken the most beloved and precious thing from me and locked her away like an animal."
He ended the letter by saying: "I hope you can find a way to forgive me."
Mrs Khan confirmed that she did not reply to the letter but instead handed it to her daughter's solicitors.
She told jurors that she had brought all her daughters up in a moderate Islamic household and that she abhorred Isis so much she could not even say the name.
Although Khan had known Rehman since she was 16 years old, the English literature graduate kept their relationship a secret from her family.
When she eventually found out, Mrs Khan said her daughter had promised to try to break it off as she knew that she would be cut off from the family if they married.
Rehman and Khan, both from Reading, deny wrongdoing.