One included $2000 from the Duchess, then Meghan Markle, for Mr Markle to put towards a holiday, and another reads: "I love you with all of my heart now and forever."
In lurid claims about her first wedding, to Trevor Engelson in 2011, he alleged guests had been given marijuana, insisting neither he or the bride had used it but that it was considered " no big deal in Jamaica".
Ms Markle, he said, had "micro-managed everything".
Asked by the Mail on Sunday about recent negative reports about the Duchess, he said: "I don't recognise this person. The Meghan I know was always sweet, kind, generous. She was always demanding but never rude."
Saying he had tried text messages, letters and a note via his ex-wife Doria Ragland, he confirmed he is no longer in touch with the Duchess or her new husband.
Relaying an alleged conversation with Prince Harry while Mr Markle was in hospital receiving treatment for his heart, he said: "I apologised to Harry on the phone and all he said was, 'If you'd listened to me [about how to deal with the media], none of this would have happened'.
"There are convicts in prisons who have murdered and committed all kinds of horrible crimes, and their daughters still visit them."
The Duke and Duchess of Sussex have never publicly responded to Mr Markle's claims. Kensington Palace declined to comment.
The intervention is likely to prove distressing for the Duke and Duchess, who are expecting their first child in the spring.
Next year, they will move to Frogmore Cottage, Windsor, and the search will begin for a new Private Secretary before Samantha Cohen, who has been in the role temporarily this year, departs.
Ms Cohen, a former Assistant Private Secretary to the Queen, will oversee the recruitment process for a permanent member of staff, but may stay on beyond 2019 if her help is still required, sources said yesterday.