Best friend’s ex keeps trying to befriend me…what should I do?

My best guy friend *Jason* was madly in love with *Sally*; who, according to him, ripped him off by thousands of dollars, while constantly accusing me of cheating on her with him (we never dated or had sex, we were like siblings).

Sally has schizophrenia and she physically abused him. She keeps trying to add me on Facebook. My first loyalty is to my best mate. I know there is a potential for Sally to be violent, as her schizophrenia is treatment resistant. I always liked her, but I feel like she could be dangerous, it would be disloyal to my friend to befriend her and that it would be toxic for him to end up back with her.

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The rest of us are not mentally ill, besides having depression and anxiety
Best friend’s ex keeps trying to befriend me…what should I do?
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