I was accused of calling CPS on my son & d/law by my d/law?

of my granddaughter. my d/law told my son CPS told her it was me who called....I have done all I could to prove that I am innocent....finally i wrote CPS and explained how my d/law was lying to my son saying they CPS had told her it was me and how the call came from my home. I got a letter back from CPS with proof that this was all a lie.I want to send a copy to my son ..what should i do