Forgiving a friend maybe?

About a week ago my best friend did something to me Im very confused about. Hes my boyfriends cousin so it was so easy for us to become close. I know the signs and what they mean but he continues to lie to me when I ask him about this situation. My boyfriend and I slept at his cousins house because they were throwing a small party. Later throughout the night I caught him snooping through my phone and was surprised to know he knew my password. I came to realize he had sent himself pictures of me off my phone that were meant for my boyfriends eyes only, and also some of me just smiling and enjoying life. He lied and told me he didnt remember doing it. I just wanted the truth on why he could do something like that to me. I assumed maybe he had fallen for me since were so close but when I asked him he said no. Ive been teased by many people stating they thought he liked me but Ive never been in a situation where A.) A family member of the guy I was dating may like me and B.) They would violate my privacy and look at my private photos in that way. I dont want to lose our friendship because weve been so close for 4 years but how do I forgive someone that would do something like that to not only me but my boyfriend? He was deleting the evidence off of my phone too so if I wouldnt have caught him I never wouldve known.. we plan to get together the three of us and talk but Im so nervous hell continue to lie. How should I even handle a situation like this?