The elder sibling shared a handwritten letter to In Touch Wednesday warning the 33-year-old royal that it’s “not too late” to stop the wedding.
“As more time passes to your royal wedding, it became very clear that this is the biggest mistake in royal wedding history,” the 51-year-old wrote. “Meghan Markle is obviously not the right woman for you.”
Thomas insisted the 36-year-old American actress is a “jaded, shallow, conceited woman that will make a joke of you and the royal family heritage.”
“I’m confused why you don’t see the real Meghan that the whole world now sees,” he claimed. “Meghan’s attempt to act the part of a princess like a below C average Hollywood actress is getting old.
"What kind of person starts out by using her own father until he’s bankrupt, then forgets about him in Mexico leaving him broke, over mostly all her debts. And when it’s time to pay him back she forgets her own father like she never knew him.”
Thomas went on to claim that their father is still struggling financially after he allegedly went into debt to support Markle’s dreams of becoming a sought-after actress. He also claimed the patriarch wasn’t invited to the wedding.
“It’s very apparent that her tiny bit of Hollywood fame has gone to her head,” he wrote. “Not to mention, to top it all off, she doesn’t invite her own family and instead invites complete strangers to the wedding. Who does that? You and the royal family should put an end to this fake fairytale wedding before it’s too late.”
Thomas concluded, “Meghan is still my sister. She is family. So whatever happens is up to her, whether she wants to forget knowing me or the rest of her family, family comes first. Also, you would think that a royal wedding would bring a torn family closer together, but I guess we’re all distant family to Meg.”
This isn’t the first time Thomas has spoken out against his half-sister. In April, he told UK’s Mirror the family is deeply hurt by the alleged royal wedding snub.
“She’s clearly forgotten her roots,” he said. “It’s torn my entire family apart. Meg likes to portray herself as a humanitarian, a people’s person and a charitable person, but she is none of those things to her family.
“She is giving the greatest performance of her life. She is acting phony. Once she got into Hollywood she turned into a different person. She’s clearly forgotten her roots and her family.”
Thomas added, “Maybe the normal American family she has is embarrassing to her because we’re not producers and executive producers. There’s a whole different side of her that has started to surface and it’s ugly to see.”
Thomas insisted he is hurt over not receiving an invitation to the royal wedding.
“I’m not bitter, just baffled,” he said. “It’s hurtful given how close we once were. I’m confused and a little distraught because here is a person knowing the position she’s in and knowing the scrutiny she’s under and yet she has forgotten her flesh and blood.
"We were so close back then, but when our grandmother died, she moved to Toronto to start filming ‘Suits’ and I didn’t see her. I haven’t seen her since late 2011.”
Thomas believed a recent domestic incident with fiancée Darlene Blount, 37, might be to blame for Markle not reaching out. The Mirror revealed he was detained after a drunken altercation led police to be called, but the matter was dropped without charges.
“No family is perfect,” he said. “All families have their disputes and troubles… Harry has not exactly been perfect in the past.”