My mother found pictures of me saved on my computer, what do I do?

I am 17 so that sucks even more. I got a new computer recently so I was giving my old one to my 8 year old brother. I guess I forgot to delete a folder called "sexting", and he supposedly found it and told my mother before opening it. She gave me a call and said she deleted the pictures but now my sister knows about it. My sister and I are really close, but I think she is going to tell my father about the pictures. My father will not take this lightly, I don't think. What do I do? Can I convince her to keep it to herself?

The pictures are just of me, nobody else. And never show my face and nudity in the same picture.