Lol why would the UK need to follow in Yugoslavias footsteps?
Have you read article 50? Do you know what a customs union is? This isnt jail or the Russian mob, countries have the right to depart if they want without pissing off the whole of Europe ,
As well as Europe being angry for two years theyve also made it as difficult as possible for the UK to leave and used the international media to trash them? So who would want to stick around for that behaviour ??
Hey, what did UK expect, that EU will reward it and give it all sorts of benefits for leaving? It is only natural that EU will protect its interests. Personally, I would not grant the UK customs union. It only wants benefits of the EU but non of the obligations. I hope it doesn't happen.
The EU did not try to make it hard to leave for you, but to protect itself from UK's disruptivness.