He signed up for internet singles website

Hi. I have been dating a wonderful man for almost a year now. We only crossed over into love and more serious territory in the past 3 months. We have both expressed that we love one another, that we can see spending our lives together and even marrying. We are both divorced, over 40 and with grown children. My problem is this: in June we were sitting side-by-side and using his laptop computer together to research some vacation websites. After he turned it on, the first thing that popped up was his email inbox where there were displayed several "thank you for registering with us-click on link to activate your account" from singles/sex websites, as well as a porn site. He quickly closed these and proceeded to open new browser and continue what we were planning on doing. I think he thought he closed it quick enough that I did not see. I admit I was somewhat in shock, so I did not say anything. That night, I used his password to access his laptop (he does not know that I know his password) and I saw the website messages again. He had not opened any of them or confirmed any of them and they were all from the same date. Well, my insecurities got the best of me, so I opened my own account on one of the websites to "catfish" and see if he ever showed up. This was almost 3 months ago and nothing. Just when I started to relax, 10 days ago 2 new messages from dating/sex sites (these are not Match.com! These sites blatantly advertise one-night stands and swinging with lots of porn-star pictures). One message thanked him for registering and asked him to click on the link to confirm. The other said they had not seen him log on in a long time and were urging him to come back for a visit. He has not clicked on either of these and has not responded to my "undercover" messages. In his brief profile on one of the sites he checked off that je was only looking for sex chat, not a relationship. He and I are about to have a very serious conversation about our future plans. Buying a house and committing. He travels a lot and we are apart for weeks at a time. I love this man and teuly believe he is my best friend. I want to give him the benefit of the doubt. I will never tell him about my undercover stuff. I want to believe that he visited these sites before we got serious and that he is no longer interested, but the sites keep sending spam. I have to say, since I signed up for 2 of these sites, I have been bombarded with spam and lots of messages from the website. Should I give him the benefit of the doubt? Or should I reveal what I have found? :-(

Reveal what you found. Don't hide your feelings & thoughts if you guys are going strong. Tell him about it & let him explain himself.