Found out my brother commited zina . Should I tell my parents?

Assalamalaykum brothers and sisters,
My 21 year old brother has been having a relationship with a girl and he has been with her for more than a year. I know it's haram and he does but he said that if your parents know than all is fine but her parents do now My know yet. He always post pictures on Instagram of them and he says it's halal but he touches her in those places which I definitely know is bad. He is going again this Wednesday to meet her and yesterday I wanted to use his camera so I went to his draw and was going to use his camera but I couldn't open it because it was jammed. By the way he was at work this time. Then my other brother said he'll open it for me and said he couldn't do it himself so took of the draw on tip of that and then he gave me the camera but then my brother saw a vibrator! First he was joking and I thought it was a microphone but it wasn't. It also had hair on it and I was shocked. Then my brother saw a packet with the word 'd' on it and he got it out and it said durex and it was condoms and we were shocked again. One was used and I remember that went to a hotel one time and I asked why and he said because they just stopped around to look. Then I looked at his pictures on his camera and there was a picture of them in a hotel. By the way it takes 3 hours for him to get there so they all planned. I didn't mean to spy but it just all revealed. He also doesn't pray but just goes jumuah and also messages her in the masjid. I am completely shocked and me and my brother think we should tell our parents but I think we should just talk to him about it instead of escalating the problem.