Parents Watch Porn!? Help?

I’m 13 years old and just found out 2 weeks ago that my parents have 6 porn discs.
It started when it was my moms birthday. We went out for dinner and somehow we got into a discusson about them having sex which was extremely awkward. I get other people having sex but with them just puts a bad image in my head. Ofcourse i get it though. When me and my brother were alone he told me that a while ago he saw a porn cd in my dads drawer.& i told him that before id seen condom flavouring in his drawer too. It was disgusting. When we got back home my parents went out again and my brother thought i was lying so i wanted to prove myself right. When i opened the wrong drawer i found a large collections of dvds. All it showed on the cover was a girls face with ‘HARDCORE’ written in huge letters but just underneath it in smaller letters you could see ’sex’. I decided to open it to make sure i wasnt misinterpreting it. When i opened it i saw dozens of pictures of half naked ladies with whips in leather and other stuff. When i opened it all the way there were 6 discs. One had a picture of a girl masturbating! Just her hand in her underwear though but it was disgusting! I thought my parents were good rolemodels but after that i was angry and couldnt look at them the same again! Now im just disgusted and still havent told them but i cant stop thinking of all those times when they went on trips or were just in bed watching that and having sex. It disgusts me just to think about it. I understand theyre humans but 6 discs it taking it too far. What should i do? Should i tell them or keep it to myself? My brother knows too and doesnt care MUCH but i still think about it. It just makes me angry sometimes. Advice from someone who’s had experience with finding porn or something in their parents room too would help. But if not any help will do.