Two lanes onto the roundabout, two off.
If the accident was because of the red person driving into the lane of the green car, the red car is at fault, and vice versa.
although if the arrow on the left hand lane really is left only then you shouldn't have collided, UNLESS the collision happened before the first exit, and not after (so you moved over too quickly, rather than him carrying on straight when he shouldn't have done.
Anyway there's a valuable lesson here, even if you win. People are stupid, and even if there shouldn't be anyone in the other lane, there might be, so check anyway.