help I need advice

So I've been dating this guy for over 2 years, and there's been multiple times I've caught him talking to other girls. Whenever I confront him he somehow manages to turn it on me and I end up forgiving him cause I don't wanna lose him. I know he loves me, we live together and we have always taken care of each other. We constantly talk about our future together and how we will be together till death basically. But it almost feels like I'm not enough for him. He barely even has sex with me anymore and when we do it honestly sucks, it feels like he's just trying to get it over with.. Anyways last night I had a weird feeling and decided to check his phone again.. I found crazy amounts of porn in his history like I don't have a problem with it but there was so much. Also I found out that he's on a couple dating websites. On one of them his bio says "I'm young just looking for hookups I'm in good shape and like to fuck". He also goes onto the personal ads on Craigslist and looks for hook ups or those stupid websites for locals in ur area. I have no idea if he cheated on me, or if he's going to but I don't know how to confront the situation. I don't know if I even want to.. he hasn't visited those websites in the last month so should I even bother? I love him with all my heart and if there's a way me and him can work it out without breaking up I wanna do that. I'm just worried about losing him... he's been my best friend for 3 years and i genuinely have no idea what I'd do without him. He's my other half..