Yeah, I'm a bit confused how you overtook him 350m before a junction and then he managed to just appear by the side of you. He was either insanely fast in which case you misjudged things, or you're a bit off target about the distances and speeds involved.
I'm fully prepared to accept that there are plenty of crap cyclists out there, I see them all the time. But at the end of the day, if something goes wrong, the cyclist will die, not the person in the car. This incident will affect all involved severly including the driver of the car.
It might just be worth accepting that the car is not king, cyclists do move faster than people anticipate and if a cyclist who you thought was behind you, appears in front of you, you probably misjudged something. It's not a slapping offense, you're only human but try and learn from it. Anticipation is probably the finest skill a driver can possess. It save petrol, brake pads and of course, lives.
Sleep tight!