what would you do?

what would you do if you snooped through your boyfriends phone and found an album of 500 pictures of asses/porn gifs/etc in his pictures? how would you confront him? especially when you know he may get mad about snooping.

I'm scared to confront him because 1. I don't like confrontation at all

2. don't want him mad

I think this is crossing a line for me considering he is proposing at the end of the year, I don't wanna go into a huge commitment with this as a problem.