EU referendum, brexit and the aftermath

A constitutional crisis is a situation that a legal system's
constitution or other basic principles of operation appear unable to
resolve; it often results in a breakdown in the orderly operation of
government.

We have no precedent for dealing with the Commons directly opposing the democratically expressed will of the British people. Everyone would be improvising and the spectrum of outcomes would range from the Commons backing down, to a general election, to a second referendum, to the Queen acting in concert with a minority government and the armed forces to suspend the Commons and implement the 'will' of the British people. I can imagine the press cheerleading the last option from day 1. Being a sort of deferential, non-confrontational people, I imagine the Commons would quite quickly calculate the possibilities and decide that backing down was the best option. I freely concede I have no idea what would happen, and nor do you, which is the point.

On civil unrest, I'm not sure I go along with your assertion that everything causes 'civil unrest', but let's not quibble. In this instance I can see people tearing up town centers and government buildings, attacking immigrants and other minority groups. Most of them have been practicing in France for the last few weeks anyway. Who would order the police and armed forces onto the streets to prevent them and under what authority?