This is all bonkers. Incredible that so much time and effort has been wasted over such a vague accusation. Your manager is a dick, their manager is a wet wipe.
It's amazing that someone hasn't just said 'For fuck's sake, where is your evidence? If you can't provide it, this complaint will be closed and @Bearyhumcrack can complain about you and the way she has been treated'.
What a monumental waste of time - and what a stress for you, op. Hope it is all over soon.