I was involved in a confusing accident at a dreaded mini roundabout. No one was hurt but both cars were written off. There was a queue of traffic coming from the right and turning right which I was giving way to. Then a car indicated left and began to turn so I took this opportunity to go, turning right. It is a larger mini roundabout so there is room to manoeuvre around it fully. I was travelling from stationary so couldn't have been going faster than 8 miles per hour but I was obviously accelerating. Before I knew what was going on I collided with a car coming from the direction I was previously giving way to my passenger side to his passenger side. I did not see him coming but my partner, seated front passenger gasped and said "wow...wow... wow" I don't know why I didn't see him or my instincts from my partner's reaction didn't cause me to break but unfortunately neither happened. I was on the roundabout when the crash happened, facing my intended exit. The other driver must have cut across the roundabout at speed behind the car which had just turned in the opposite direction as this is the only way we could have crashed passenger to passenger. Who is at fault? He claims me for not giving way to the right. I claim him for not giving way to traffic already on the roundabout. He is claiming I am 100% liable. What happens now?