I didn't come here to out anyone, just to get some advice on how I recover from this emotionally and on strategies for protecting myself in future.

I've paraphrased the descriptions of the other people involved to protect their exact identities and relationships with me. The exact details reveal the worser extent of the betrayals.

I'm not going to out them here because it's not considerate of me to make the choice on their behalf, to expose who they are on HN.