I was going through the files on canvas of my course, then I saw a file called like Examination_(coursename)_2021 and was like "it's probably the practice". I opened it and it seemed like the actual exam, so I sent a message to course group like is this the actual exam? It seems like it is and they asked me to share it with them, which I did. Then I started thinking I should tell my professor that I have access to the questions. I also checked if other people in my class could find the file which they did. So now I'm kind of lost, obviously, I want to do well on the exam but also I don't feel good about it. Although the exam is tomorrow and it is an open book exam, I feel like I should tell my professor just because now my mind isn't focused on the exam at all, I feel I am morally obligated to tell them. Though I would have to tell everyone in my group that I told the professor which I don't think they would be happy about because I asked them if I should tell the professor and they already said no. Another reason I'm worried is that the professor might be able to see when I first viewed the questions, which was a day before, I'm just so lost about what I should do.
I think I will tell my professor. However, now I don't know if I should tell the people in my class or just keep it anonymous. I'm worried that if I don't tell my class, some people will only have prepared for the questions and not for the actual course. I definitely regret sharing the exam with the people in my class now, it would've been much easier to have told my professor, if I hadn't shared the questions with the people in my class.
Edit 2: So I did send an email yesterday and apparently, it was just a past exam from another year. So it's all good. I just completed the actual exam today and feel quite good about it. Thank you to everyone who helped give advice!!