Why is he on this site? And am I over reacting?

My boyfriend and i have been together just over 2 years now. Ill be the first to admit i have trust issues i was in an abusive relationship 2 years previous to my current and he used to cheat on me. I met my current partner and he was prince charming, he has treated me better then i could ever imagined, yes its not a cinderella story everyday but as relationships go i think we have a strong one, our sex life is fully there, we still have sex pretty much everyday, days off even nurmeous times. His always been a bit funny with his phone flat side down ect but i always just thought i was over thinking it and put it to the back of my head. Then about 6 weeks ago he wasnt that intrested in having sex for about 4-5 days kept saying he was tired, which is not like him at all. At the start of the week i decided to check his phone and seen he had been watching porn everyday and im not just talking one video numeuos each day. I then checked his phone a few days later still not having sex with me and looked again, i went through his interent history and found not only had he been on porn but he had been on a swingers site. (Which this site in particlur isnt just for couples, its all and anything). When alone i went on the site and made a profile so i could see how to find stuff out. A fake one at this not me or my name. Then when alone with his phone i clicked on the site, which i found he was actually on it his own profile, hidden but still active. I clicked in the recieved messages and the box was empty i then clicked in the sent messages and found one single sent message from 2 weeks previous asking if a couple were intrested in having fun with him. His name. And age. I started shaking and didnt even look at anything else. As soon as he came out the toilet i asked him if he had cheated on me, whilst crying my eyes out. He went straight to his phone, picked it up and said what you on about. I then clicked his internet with the phone still in his hand and brought up the sent message, read it out to him. And he denyed sending it. His name at the bottom was spelt differently that was his excuse thats not even how you spell my name. I then told him his been on the site all week, actually searching for women in our area. After letting me press the friend button (which there were two friends there, one pornstar and one women from the next town which i dont know) i then clicked on pictures and there were two pictures of his face and a picture of his penis in a private folder which when going to look at the penis picture he then snactched the phone off of me and said look ill delete the profile, pressed a few buttons then kept hold of his phone. I cried my eyes out to him, asked him what it was all about, he then told me he just goes on it to read the stories he had created the account when he was with his previous partner becuase his work mate had said if your not getting any sex at home, get on this site. Told me he never met anyone off of there and only wants me. I know a cheater and he acted all the right ways. I had to go to work aftet this, i then gave said to him to tell me everything or anything that could effect our relationship in the future now and ill try my best to put it behind us if he truly does what me after he had said i satisfy him sexually and im all he wants there was nothing else he said. I told him i was fine with him going crazy with porn if he wants but i couldnt cope with him looking at people in the area in that way. He said he wouldnt. So about 2 weeks ago i remembered id made that fake profile, i went on it thinking to delete it as it was all behind us, but before i did that i typed his user name in and low and behold it was there but said profile is hidden, i added him to a hotlist which still wouldnt let me see his profile but i coukd see there were 2 private photos in the box and it also said when he was last online a month ago. Feeling confused as to why the profile was still there at all, i checked on this fake one to delete it as he deleted it in front of me, well thats what i thought. And it came up with one last are you sure you will not be able to get the profile back. I went off it, i contemplated asking him but ovbs that would mean he would know i knew and i didnt want to give him any reason to go back onto it. Still having sex everyday, me still occasional looking at his history, porn on there but no swingers site. I felt a lot more relaxed, still wondering though. So id say its been 7 weeks since this all started. 3 days ago i came away for my friends hen party, were going home today though. I woke up after a bad dream, my gut said check so i did About 2 hours ago and it says he was last active 1 day ago. I honestly dont know what to do? Im in spain, i dont want to say it over the phone or to be honest when i get home. I asked him last time after seeing proof of the message and he denyied it. I gave him a chance and he said there was nothing. Part of me whats to wait and go on the site again to see if theres more messages, some proof for my own eyes so he cant just deny it. Weve moved into my mums so we can save for a morgate together, so its not like his got anywhere else to go. Im crazy about him and id do anything for him but i have to have respect for myself i wont put myself back where i was before but is going on this site cheating? Has he got an addiction to it? Am i just making up excuses for him? What the hell do i do today? Please tell me if im stupid?