My ex boyfriend of 3 years stole my sisters sex tapes

I am a 19F and was with my ex 19M for almost 3 years (our 3 year anniversary is 2 months) It was my first relationship and i lived with him the moment I turned 18 for 1 1/2 years. As this was my first relationship i still have yet to process the full extent of his actions and emotional/psychological abuse. Last month, i was planning his surprise birthday party, so i went on his phone to screenshot his close friends list and send it to myself to make a guest list. I deleted it off his phone but the screenshot ended up not sending, so i go to his recently deleted to see him recording my sister’s (22F) phone. He went into her hidden folder and took a private sex tape she took with her partner. It was a few days old, when i saw this my stomach was fucking turning and i started shaking so fucking much. I go up to him and just start staring and hyperventilating, he keeps asking whats wrong then RUNSSS to his phone. This mf has the audacity to say “wait let me explain” i am in so much shock i just start crying and he leads me to his backyard and start rambling about bullshit. His excuse was a “friend” was “pressuring” him and he was low on money and the friend was offering it for my sister?? Makes absolutely no sense. I run back inside the house and immediately start yelling his sisters name. His sister and her gf and also his parents all come out of their room. My ex then put both of his arms around me and starts trying to drag me to the backyard while telling his family that im about to say something “out of context”. His sister tells him to shut up and let go of me then asks me directly what happened. I scream that he has naked videos of my sister and collapse to the floor and his mom starts hugging me and apologizing over and over. I get taken into his sisters room and try to calm down while his sisters gf is trying to keep him out of the room. Im in the room alone for a little until his sister barges into the room crying and saying “he did it to me too! he did it to me too!” this disgusting pervert ended up telling his family that hes known this “friend” since middle school and in middle school he tried paying him for his sisters nudes but never went through with it. He claimed he never ended up going through with my sister either and he never sent them but he literally had the videos on his phone??? It been a month since this happened and he has since then deleted everything including our private videos, as far as i know. His sister says he is a pathological liar, I feel completely blindsided, disgusted and just distraught. I have to rethink everything he has ever told me. Yes my sister know about everything now, I feel so sorry for her having to be involved in this crazy situation. Ive been considering blasting him on social media while also keeping my sisters identity hidden. But he is also still paying me back 5k that i lent that bum. Also have been considering going to the police but i literally have no evidence. I dont know what to do and how i could get justice of if i genuinely just have to move on knowing he can walk around like he didn’t traumatize me and my own sister, who is not only my sister but actually my best and closest fucking friend.