To hate that feeling when you suddenly realise someone isn't trustworthy

[power10]

I have a friend, someone I considered to be my best friend. I would tell her everything and thought it was between us.

Anyhow, it seems she has new friends too (fair enough!) but has been telling these people, who I've met briefly, all of my life gossip.

I shared with the friend that I was struggling with dp's infidelity. She then told a new group of people!

What's more, said friend has been bitching about me behind my back. What is wrong with people?

You'll have to gently let her go, won't you? Not much you can do otherwise.

I'm so sorry to read this power10. You must feel so upset and let down. Obviously you can't trust her to behave appropriately with anything you confide to her. And when someone you consider to be your best friend does that it's devastating. The thing is friendships evolve all the time and unfortunately this one is going in the wrong direction for you. I'd let the friendship fade out over time, if that's easiest for you. Sometimes when life's worst moments hit you find out who your real friends are.

I've had this recently too OP and it really sucks. It's happened with three people (separate issues) - one of whom landed me in hot water at work (despite the fact that I am completely blameless in the issue she had been mistakenly referring to and she had made a weird assumption too) - luckily it blew over quickly . Another colleague, also considered a friend and someone who I have done countless professional and personal favours for, boycotted my (award winning) project that directly fed into his project. The third was just mostly thoughtless and inconsiderate.
It got me down A LOT at first so I can totally identify with those feelings you're having. It's a shock and honestly I would never have behaved in the unprofessional and and mean way these people have , friend or not. I can see how they're shit stirring and jealous so it's probably a good thing long term for me to remove myself from them. They're all wounded though as if I am ghosting them for no reason. However, they don't get the best of me anymore - why would I waste it on people like that?!

That’s really sad. Suggest ending the friendship and all contact completely.