He dropped out of the wedding party with days to go and has claimed since that Meghan won't speak with him.
In pristine handwriting, the Duchess of Sussex accuses her father of having broken her heart "into a million pieces" by having given interviews to the press and having fabricated stories and lies, attacking her new husband.
In her letter dated August 2018, quoted by the Daily Mail, Meghan addressed the feud between the two and began: "Daddy, it is with a heavy heart that I write this, not understanding why you have chosen to take this path, turning a blind eye to the pain you are causing".
In the handwritten note, Meghan is said to have accused Thomas Markle of "unwarranted pain" and "making the choice to not tell the truth". "Something I will never understand", she wrote.
In the letter the duchess pleaded with him to stop "lying" to the press writing, "If you love me, as you tell the press you do, please stop". Please allow us to live our lives in peace.
Since then Thomas and Meghan's half-sister Samantha have continued to speak critically of her to United Kingdom tabloids.
Meghan, who's expecting her first child with Prince Harry (34), apparently wrote the letter to reach out to her father.
Mr Markle was referring to the fact that information about the letter was revealed to the world because of an anonymous interview that five of Meghan's friends gave to People last week. "I begged you to accept help - we sent someone to your home...and instead of speaking to me to accept this or any help, you stopped answering your phone and chose to only speak to tabloids".
He said: 'I thought it would be an olive branch.
Meghan also admonishes her father for siding with her half-sister Samantha - who has attacked her in the press - while she "silently suffered at the hand of her vicious lies".
We all rallied around to support and protect you from day 1, and this you know.
Meghan also accuses her father of snubbing her and Prince Harry's offers to help when he pulled out of attending their wedding following two heart attacks and accuses him of being ungrateful for money she has given him.
Kensington Palace declined to comment on the letter.