Hello, thank you for the question. I'm sorry that you went through this, it sounds horrible.
Firstly, while discussing this please don't use any specific details that might identify you. You're facing criminal charges and you don't want to say anything here that can be attributed to you directly which if the police find it for any reason, could be used against you. I'm not your retained counsel so we have no solicitor-client privilege in our communications.
You ask if you have grounds for a civil suit. I can't guarantee that you do, but it sounds to me that it's very likely. Much will depend on whether you have a specific diagnosis which the police could have discovered if they had bothered to check once you told them about it.
It's good that you have pictures and some records, please keep trying to gather information and keep a journal of who you speak to about what regarding this case and what information you get from whom.
See a civil lawyer as soon as possible. Finding one who will bring an action against the police might take some searching, but they are out there. That lawyer will likely not want to start an action while the criminal charges are outstanding, but you'll have to go along with what they recommend.
You'll need to quantify your damages, so think about the ways in which the actions of the police caused you harm and think about what specific dollar value could be reasonably attributed. To get a large dollar amount for pain/suffering or punitive damages takes a highly convincing level of evidence so please don't assume you have a large payout coming.
This is certainly the right political environment for such an action; the police have been under fire lately in many jurisdictions for being heavy handed when dealing with those who have a legitimate mental illness.
Is there anything else to discuss about this? If I've answered you then I'd appreciate a positive service rating please.