Thomas Markle Jr. is asking half-sister Meghan Markle and Prince Harry for forgiveness in a touching letter he wrote on "Big Brother VIP."

The former window fitter penned his apology letter as part of housemate Luke Toki's "secret mission" to have him write to the Duke and Duchess of Sussex. In response to the challenge, he said, "I'm here to prove to myself and to the entire world that Tom Markle is an awesome person" and added, "To show Meghan Markle I'm not the jerk from the tabloids in this whole big misunderstanding."

In his letter, he confessed that the first one he wrote to them in 2018 was the "biggest mistake" of his life. He had urged Prince Harry to reconsider marrying his sister and called their nuptials "the biggest mistake in royal wedding history." He had also called his sibling a "jaded, shallow, conceited woman."

But on Monday's episode of "Big Brother VIP," Thomas Jr. had a change of heart and asked that he be forgiven for the things he had said. He opened his letter, "Dear Meghan and Harry, the first thing I want to say to you two is that I'm sorry from the bottom of my heart for the awful, mean letter I wrote to you prior to your wedding."

"And I want both of you to know it did not come from the real person that I am. But came from a very dark and hurt part of my heart. I am not a mean person at all and I have more love inside me to give than anything," he continued.

The Oregon native said the first letter he wrote came from him "feeling really hurt and confused" when he was informed of Meghan Markle's response that he "was distant family." He said he was offended "because of the amazing bond and relationship" they shared growing up together.

Thomas pens a new letter to estranged sister Meghan Markle. #BBAUvip

— Big Brother AU (@BigBrotherAU) November 8, 2021

"All I could do was put up a defence wall to protect my heart. I know that it was very immature and wrong and I truly regret it," he added as he admitted that he feels like a "complete a**" for what he had done.

Thomas Jr. said that he lost his privacy when his sister's relationship with Prince Harry was made public. He remembered it being "very, very stressful to have to deal with" becoming a public figure "all alone with no help at all."

Thomas Jr. said that what he really wants to tell Meghan Markle is that he is "so proud" of her and that he is "so happy" for her and Prince Harry. He closed his letter, "I truly love you guys...I wish you Meghan and Harry, Archie and Lili the happiest, most loving life possible."

Prince Harry and Meghan Markle
The fairytale wedding in May 2018 was one of the events of the decade Photo: POOL / Ben STANSALL