Revenge porn situation. please help

I am 21 male .The scene starts for here. I have a relative which we call mama (mummy's brother) . He is mama by very far relations. We didn't have that much connection with him until my sister met him occasionally 4 years ago. That time I was living in another city. When I came here my sister introduced me with him. My mom knows him very well. he is kind of belonging with village mentality. He did engineering and had a job that time. My family was somewhat week financialy and mentally because my father retired in middle of our ongoing education. My sister 24 and he 32 had a good friendship. He comes in our home takes us out for hangouts, movies. He was forcibly trying to mix with our family. It was happening since 4 years. But one day my mom told me that he asked her that he wants to marry my sister. My mom and me was shocked because it was weird. We see them like mama bhanji and how other relatives except him and so so.. .. We took decision that it can be possible after the marriage of my older sister. So my mom told him to wait for 2 years. One day I found some suspicious activity that they(my sister and mama) were exchanging some big size vedios and facing some problem . I am very good at technical things they always used to give me any task related to this type. But at this time they were like doing themselves going through that. So I predicted that my sister is also in relationship with him and they are exchanging their self made mms. I was like not able to accept this thing but my mind was torturing me. So I investigated it and yes I was correct. It was their mms. I was like out of my mind watching my sister naked.I kept this in my mind for 2-3 days but after that I took whine. After drunk I came home and told everything to my mom. My mom was also got out of mind. We asked my sister that we have to go to his house and fix their marriage. But my sister denied. Days went. One day I messaged him to delete all their mms. He told that he already deleted. But I did some wipe data techniques to delete them hard. I did not wanted to talk him anymore. Days went After 6 months he messaged my sister that he is going to engaged with someone else and she was crying and told us that she wants to marry him and they had plan of marriage Since 3 years. He promised her to marry and than after my sister got ready for sex. In between he also tried to tell my mom and sister that he wants to marry this year only. After his engagement information. We called him and their family was like on fire that why we are calling them if we were not ready for marriage . they tried all the excuses for escaping him. He betrayed my sister doing false marriage promise and had sex. We are not talking to them and we don't want our sister to marry such fraud person. The problem is my family thinks that he still has the mms and we after watching his cruel face we are worried that someday he will upload it on internet. Mms content : In the mms they are kissing each other and both of their faces are visible. Somewhere upper part of my sister is also visible. They are kissing and laughing. Lower part is not visible. We are thinking to take police to his house and search for every storage device and delete the mms if any. I also. Know we can send him jail for 18 years. According to law of doing sex under false marriage promise and law of dhoka dhadi. What are other laws related to this case. Please help me what should I do.