So you say.
I am not blaming you. I am pointing out the weaknesses in your description of the goings-on.
If it ever does go to you having to argue the toss in court, better you've got your version watertight and truthful, than to be left floundering.
Without other witnesses and/or dashcam footage, it is just as likely that you (not paying attention) merged into the rear quarter of the car on your right.
If I was defending the other driver, that is the approach I'd take.
Whichever way the land lies, I don't think it quite warrants a driving without due care slapped against it when there is no other evidence other than he said she said. Had it been any other person the police wouldn't have got involved and left it to the insurance companies to sort.
I didn't try blocking or anything like that. The police also have to prove beyond all reasonable doubt that I was driving without due care and attention