applications – How to find hidden applications

The other day, my boyfriend told me that he had a record of ALL the activity of my phone for the last 11 days and that he had not yet reviewed it. I would like to know how it would be possible? Did you put some hidden application on my phone or could I access it from your phone in some way? It just makes me feel uncomfortable having zero privacy, and I'm wondering if I should disable something or how to find some hidden application that allows it. Thank you.