I found SIL's posts on reddit and it turns out she is considering undergoing operations to become a man (except she has no money so possibly wouldn't do anything). She is v socially isolated, earns 400-1200 pounds online writing online but otherwise stays in her room all day, is fairly nocturnal, dropped out of school. Diagnosed with ADD and aspergers as a teen but family ignored the diagnosis. She is an adult but is v dependent on her mum and i consider her vulnerable.
Should i tell her mother? I think it would be very detrimental if she found out i read her posts online and she would explode. Not sure if I could trust her mum to keep a secret. In addition mum hasn't really done anything re her other aspergers and ADD so maybe not much point knowing. but I think if I was her mum I would want to know.
Thanks all.