Hi 8888an8888, the "absolutely" in "absolutely furious" is a massive understatement, right???!!!
In terms of the message, obviously he has severe "problems" and maybe it wasn't meant to hurt you, maybe he thought that he was being nice in his perception........but the message was still totally "UNACCEPTABLE". I don't know if a restriction/no contact order from the police might be possible, as he is "in effect" still trying to contact you........could you have the hospital or unit check this out for/with you??
But regardless, please talk to the staff about the "incident", as there's no doubt whatsoever either that your mom is completely out of line as well. She should be wanting to protect you.........and to still be attached to him!!!!! Maybe they or the unit, could work with her on getting an REAL understanding, or minimally they could support you in "handling" her reaction/s. Although if this is a reflection of her attitude towards things maybe you can do with some (a lot of!!) space from her as well.
I am so sorry this has happened to you though, just please reach out for all the help/support they have to offer you, at the hospital and the unit. You deserve it!!!
And keep talking to us as well, hey?? We care!!

Alison