We do only have one side of the story.
It's possible to imagine (screen goes wavy, harp music...)...
...that there was a mobile altercation - perhaps after a close pass, there was an exchange of gestures, followed by the driver threatening to hit the cyclist with her car, and maybe managing actually to do so.
Fearing she's done some damage, maybe she stops to check.
Meanwhile, the cyclist, thinking he's dealing with someone quite willing to kill him (it is someone who's just driven a tonne of metal at him, after all), finds the car door opening and gets his defence in first. Maybe he never realises he's dealing with a woman at all.
(and back to reality...)
Misunderstandings all round. But we're hearing the woman driver's pre-emptive version of the story, in which she of course is entirely blameless - except that she "thinks" she hit him.
Let's not get so far carried away with this "it's never defensible to hit a woman" idea that we forget nobody should be hitting anyone, of either sex, with their fists or with a car, either negligently or deliberately.
(In fact, I think you could argue that, of the two, hitting someone with a fist in a fit of temper is probalby a lesser crime than hitting someone negligently with a large, fast-moving vehicle - against which there is little option for self-defence. I'm not making this argument, just mentioning it).
But if it's me getting hit, I'd much rather it was the fist.