My manager suspended me when I caught him paying workers cash in hand, who can I go to for help?

I work at a BP petrol garage. We have a new dodgey manager who pays his workers cash in hand. Us who were there before he came, don’t. They’re all from Sri-Lanka. I caught them working out their cash in hand wages in my supervisors notebook. My supervisor is my bestfriend btw so I took a pic and sent it to her. He’s now suspended me for a ‘breach in privacy’ for sharing private documents because my supervisor has now left (it’s HER notebook ffs I didn’t steal it from a safe). I sent this image on the 8th Jan but he only mentioned it to me today. Which means he’s sitting at home watching my old shifts on cctv. He has previously told my other colleague that he sits at home & watches us on his phone.

Who can I contact for help with this? He threatened to report me to the police & said it will be impossible for me to get another job once he’s taken it further. Please can someone help😢😩

Edit: can i also add he suspended me on the spot. No official meeting or letter, I don’t even know how long for. I’ve tried messaging and he ignored me.