Please Help with the confusion!?!

About three days ago I found on my boyfriends history a website called naughty date that he went on over Thanksgiving while I was away only three times. He says he didn't talk to anyone. I did it looks like you had to pay to talk to them. I looked it up and saw you needed to make a profile to look at the profiles. Clicking on his history I saw that he made a profile and add a picture but that's really it. He is going through a lot and lost his car and just going through a lot. Before we even started dating he said he wasn't into dating sites. And just 5 days we celebrated are year and a half. It's just so unlike him to even be on a dating site and I just am confused because I have had no reason to doubt him until now. Also this is are very first fight. I guess I don't know if I making a huge deal over nothing or should I leave him?