This thread doesnt make any sense.

If what you're saying is true, and you were already on the roundabout, she hit your passenger side from an entrance to the roundabout, then it is 100% her fault. There is no ambiguity whatsoever.
If the police are suggesting 50/50, report the officer dealing with it to a higher authority, as they're probably just doing it because they are lazy useless fuckers.

And where has a blackout or act of god come into it ? Is someone suggesting she did have a lapse or something ? And then suggesting you were at fault ? 1+1 doesnt = 54

As Rog says, ALWAYS take photos of the scene, cars involved, damage, the road, people involved etc etc. Everyone has a camera these days on their phone, so there is no excuse for not recording all of this on camera.
People lie, the Police lie, everyone tells lies. The camera only records facts.
And also write down exactly what happened NOW if you havent already done so. Do it before you forget any details.

And if her husband is blaming you, being aggressive, record this too. Dates, times, phone calls if any, whatever.

Old or young, sounds like the other driver was totally incompetent. You should also be pressing the police to have them prosecuted for dangerous driving
They'll proactively hunt drivers down for doing 35 in a 30 and causing no harm to anyone. Yet some numpty actually crashes into someone causing destruction and harm, and the police do fuck all ?

Is it any wonder I have the legal system here !! Persecute innocent motorists, then let the ones who cause harm walk free.

And in-car cameras are cheap these days. I have one running al the time in my van to record facts should something occur.