My Child viewing inappropriate videos

Hello,​I recently walked in to find my son (8 yrs old almost 9) on his tablet covered (himself and tablet) with a blanket watching something after school. I walked over and asked him to take the blanket off, with my premise being that its bad for his eyes to be that close to the light of his tablet. He slowly took the blanket off and I realized he was watching looking at some strange porn videos or at least searching for them. We thought we had set up the Amazon fire browser App Silk to block this type of content but we must not have correctly (we are now).​What I saw were some intermittent searches over the past 2 months. Basically you see him search for some foot activity, farting on face activity, and twerking activity. You could see popups or links he clicked on coming up as well, as with any internet site you get suggested ads etc. Looking at the searches, you could see he would search for basketball highlights, then randomly look at some inappropriate videos. This weeks later, he might look at some inappropriate videos, then start searching dude perfect or baseball home run videos. So it was sporadic, but there was a trail. I think I approached it ok by not yelling, not demeaning or anything. I just asked where he learned about these videos (named a friend from school) and why he wanted to look them up. He said he was curious and was extremely sorry. I told him not to be sorry and that I'm not mad at all. He said he found them gross, but I am not sure if that was just him covering for himself to make me believe he wont look anymore. I told him I have to delete that app, because while I'm not mad at him for being curious, it is not good stuff for him to look for. He seemed to understand and even followed up later as I was trying to review his searches and figure out how to delete the app. He kept asking, if I found out how to delete it and if its finally gone now.​So has anyone else dealt with this type of thing? I feel so sick to my stomach because I'm not sure what the long term impact is here and I also feel like some of his innocence was hindered.​Thoughts? Experiences? I feel awful thinking about it. via /r/Parenting http://bit.ly/2IMoCKN