😱I caught him....searching naked pictures on line😱

I don't know what to do.... i was on the lap top clearing the history. When my husband and I noticed Someone was searching naked pictures, 😱😢 I shouted. "Naked pictures, who in the f@€£ was searching that?" right away he yelled and said, " it wasn't me". with a scared look on his face... Man my heart dropped, I didn't know what to think, or to say to him....I finally look at my husband and tell him, "what should we do?" he shrug his shoulders and says " I don't know"..... I know I didn't mention this in the beginning but my son is only 10yrs old, he's my only and oldest Boy. I have 2 girls who are 7 and 3 yrs old...they wouldn't, shouldn't even think of typing something like this....well my husband and I are trying of a way to approach him with out him feeling scared of us to talk to us about anything... but I told my husband to ask his friends for advice, what would they do In this situation? please help mommies....