Pippa Middleton's recent engagement to James Matthews should have been a joyous occasion for her family, but instead, it's caused tension between the 32-year-old and her sister Kate Middleton.

The Duchess' main concern isn't with James himself, but with his younger brother Spencer Matthews, who has appeared on multiple reality shows and openly admitted to experimenting with cocaine and LSD.

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"[Kate] is horrified about Spencer being Pippa's brother-in-law," a source exclusively tells Life & Style.

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"Spencer has slept his way around London and left a lengthy trail of angry women in his wake," a different insider reveals. "Kate's concerned. The last thing she wants is for William's family to turn against her because of Spencer's actions."

We foresee plenty of royal drama ahead!

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