I found a number........

So I was getting something out of my husbands wallet and a little folded piece of paper fell out. A receipt. I thought nothing of it and was putting it back in when I saw it was a number, a phone number. And I know it could mean anything but I felt a pit in my stomach and I want to cry. Things have been sort of rocky between my husband and I and I couldn’t help but think the worst. What should I do?? I was gona call it to see if a female answers, but I still haven’t gotten an answer........... am I psycho???????