reversing Brexit is possible, here is a short explanation: https://www.youtube.com/watch?v=gLrzMzD_yvw

the question isn't if the EU still wants the UK (but that it's unlikely that in the current local political internal climate and the opposition it isn't likely. Though certainly legally possible.

the danger to the UK automotive sector: https://www.youtube.com/watch?v=Pq2Z9uHzsGM

edge cases such as aviation (not a fan of Ryan air CEO but still worth watching): https://www.youtube.com/watch?v=Inr1KEoJqJ0

and here a longer one about the effects of Brexit - it is worth every minute IMO: https://www.youtube.com/watch?v=EcIkIz98zXU&

Of course you can stop it. UK Parliament would just need to annul the Article 50 withdrawal bill. But the question is whether there is the political will to do so.

It's very tricky because Brexiteers/Remainers cut across both Labour and the Tories and yet the party members are expected to toe the party line. Which results in an impasse.

"just"

The complete agreement of every EU nation is required to un-invoke article 50, because there are no provisions for it. Now, they'd likely do it, but that isn't a certainty, especially as the UK arguably gets a lot more out of the EU than most other member states relative to investment.

Meh, tons of member states are "sources of political risk", that's the nature of large-scale politics.