I caught my best friend s leeping with my son

I came down with the flu at work several weeks ago, so I went home — only to discover my 22-year-old son and my 43-year-old best friend in b ed. They were not s leeping. I am at a total loss. I have no idea what to say to them. All of us are super embarrassed. Am I a prude? Ugh!
I don’t know what to do.