How to react to this situation?

I [19M] sent someone a dp on snap and in response they accused me of sending cp. I told them I’m 19 and they said it’s evens worse that I’m an adult and sent an indecent image of a child. I did not include my face in the image and you can’t even see my full dick in it because I’m wearing underwear.

The person said that the reason they think it’s cp is because it’s too underdeveloped and they are adamant that I sent them a “child’s genitals” . Is this not incredibly weird.. first of all why would I send anything other than my own, and secondly I would never in my life be in possession of cp never mind distribute it. What do I do in this situation