I would be very suspicious of this scenario.
To me the driver of the car that "cut you up" need not have returned. You may have been the victim of an accident that was set up. Let your insurers sort it out, that's what they are there for.
There are often accidents at roundabousts. You are best to go with the traffic flow. If you are in the wriong lane you can't expect to just indicate and pull out.
However, there is no excuse for the driver behind to go into the back of you.