I am pro-European. Despite its many failings, I believe the United Kingdom is better off in the EU, and I think the EU makes Europe a safer and more prosperous place.
Views differ, and even in the Labour movement there are those both for and against Brexit.
There is an organization called Trade Unionists Against the EU. I repeat that I am against Brexit, but I think the arguments the TUAEU set out are at least worthy listening to.
Take a look here - http://www.tuaeu.co.uk/