As part of my blue light driving course we were made to memorise this...
"You MUST NOT overtake
if you would have to cross or straddle double white line where the line nearest you is solid unless necessary, provided the road is clear, to pass a stationary vehicle, or overtake a pedal cycle, horse or road maintenance vehicle, if they are travelling at 10 mph (16 km/h) or less.
if you would have to enter an area designed to divide traffic, if it is surrounded by a solid white line
the nearest vehicle to a pedestrian crossing, especially when it has stopped to let pedestrians cross
if you would have to enter a lane reserved for buses, trams or cycles during its hours of operation
after a ‘No Overtaking’ sign and until you pass a sign cancelling the restriction."
We had to score 95% on the exam writing this out from memory to pass (and misplacing a capital letter or a comma was a point deduction let alone the wording) this is how much importance is placed on this one rule from the highway code (the format of the rule has changed slightly in the last 2 decades so I've had to cut and paste two together to get what we were made to reciet).
If you break this rule it is dangerous driving, if you kill someone whilst breaking this rule it is death by dangerous driving which carries a custodial sentence.
OP you were absolutely correct to drive as you did, the other drivers were inpatient and dangerous, do you have a dashcam that you could send the footage in to the police via the online reporting site?