I don't think you should have to explain yourself at this point. Johnny has dug his own hole and needs to just lay in it. You were within 2 years of each other. As long as you didn't possess nudes of her, you are legally just fine. I owe you an apology for assuming what half of the year your birth could have fallen and your intentions in getting with her. I projected my own experience as a teenager with older men on the internet onto you and further misunderstood why you were not named earlier in the document when you were talked about, if you were a coauthor.
As for Johnny, the screenshots are all there, legally he's already screwed himself by loudly admitting what he did and then threatening to sue, and giving out more and more information, then redacting it.
You've got a great case. The only item he can contest is grooming, which by definition would be him as the initiator of all sex acts, due to her interactions. However, Grooming or no grooming, you can still bring him up on charges.
The best thing you can do legally and for your girlfriend is stop trying to respond to all the claims and redact the document to reflect only the relevant information, which is Johnny sexting her and sending his penis, the scope of the relationship time wise, and him continuing to interact and send money. That is an ironclad pedophilia case.
Edit: I think your doc was reported. I hope you still have everything
UNCLEREGZ
def lookin up for more
preach brotha preach