Hello need some advice in regards to what my 5 y/o son said to me while we were driving to go get groceries.

Back story his mother and I have been separated for over a year now, getting the divorce filings under way and today he said to me not in a question but a statement of " dad you and mom aren't together anymore because you cheated on her" in which couldn't be farther from the truth. I documented it in our family app that we use to communicate through is there a need to bring that up to her at all or bring it up in the first cmf meeting??