The Sussexes were snubbed from an invite to Balmoral Castle, which may have been the last straw for Meghan Markle and Prince Harry.

The couple may have hit their last straw (Image: Getty)

Meghan Markle has been open with struggles of mental health in rare public interviews and now she could share even more in a tell-all memoir, says an insider.

The Duchess of Sussex, along with husband Prince Harry, were reportedly snubbed from an invite to Balmoral Castle this year which could be a last straw for the couple.

Meghan, 43, has in the past said she battled suicidal thoughts during life as a royal in the UK, and in a joint interview with CBS last week, briefly shared details of her experiences again.

She told CBS interviewer Jane Pauley: “When you’ve been through any level of pain or trauma, I believe part of our healing journey, certainly part of mine, is being able to be really open about it.

“And I haven’t really scraped the surface on my experience, but I do think that I would never want someone else to feel that way, and I would never want someone else to be making those sorts of plans, and I would never want someone else to not be believed.”

If the Suits actress does share her side of the story, it could cause the fued to become “nuclear” says an insider.

The source told Closer: “The talk among their friends is that it’s time to take the gloves off and do away with the diplomacy.

“There’s so much demand for Meghan to speak out, whether that’s in the form of another sit-down interview or even her own memoir. She has the potential to make an absolute fortune and clear up a lot of questions.”

Meghan first spoke out about her suicide struggles on Oprah (Image: Getty)

The insider reckons the Sussexes not being invited to Balmoral is a big factor in their decision to fight back.

They added: “It doesn’t exactly shock Harry and Meghan that they’re not invited considering they’re not even on speaking terms at this point, but it feels very much like a personal attack designed to hurt and embarrass them.

“It’s not just about pride or hurt feelings, there are very ugly repercussions for them when this constant narrative that they’re family outcasts keeps getting fed. It impacts their brand as well as their morale, and it has the potential to put them more at risk.

“They’re now being forced to figure out a strategy to fight back, and one option on the table is to go all-out with a big tell-all from Meghan where she completely lays out her side of the story.”