How to address my boyfriend's problem?

Hi, I'm very new here. I have been with my boyfriend for about five years. I always was aware that he watched porn, but I think it has reached a new unhealthy level. Our sex life has always been fun and interesting, although we did break up once and at the time he said he stopped wanting to have sex and he didn't know why... I think tonight I discovered the reason. I found out through an email that he pays money to watch a certain woman make videos of herself, besides the countless free websites he visits. His attitude has completely changed and he has always joked about the amount of porn he watches and mastrabating, but I'm starting to think they've never been jokes which means it's a daily habit. I don't know how to address the issue since he doesn't know I have access to his email, but I know I need to.

I feel like something is wrong with me and like I'm not making him happy enough, although I know that's not the case. I love him, but I'm more insecure than ever. I will never be like those women, nor do I want to be, but now I feel like he's not even attracted to me. We've always kept things interesting and rather kinky, but what if he just wants to do things he sees other women doing? I now feel like he's pretending I'm someone else. I also feel like the passion hasn't been the act is more about finishing than love.