My boyfriend watches porn

So last night I found out that my boyfriend watches porn. We were in his car and he turned on the Bluetooth so I could play music through his phone. His car has a screen in it that shows what you are listening to and it also shows what you last listened to. It showed the porn he had watched. I noticed it first and didn't say anything but as soon as he noticed he tried to cover it up. I don't know why I'm so upset about this! I have have watched poem in the past but not since we started dating. I don't what to do. Should I confront him or let it go .