Agreed. All in all I don't think Brexit was a good choice.But have you considered that there is a risk of thermal shock and cardiac arrest? Many people die from cold water shock swimming every year. Particularly the older and less fit and able. It's fine to say "it won't happen to me" but what evidence have you got to say that it's safe to do so?
As for the united states of europe - I might not agree with continuing political union and a federal EU superstate, but it isn't the worst case on offer here. Have you not stopped to think that this spineless bunch of MuPpetS so poorly negotiating our brexit will be the same lot who will run in desperation for a trade deal with uncle Sam? Have openly said that is a priority? Uncle Sam is not one for giving anything away unless it suits the US agenda. So with Brexit we'll either end up a vassall state of the EU or a vassall state of the US. Don't tell me we won't, we won't have a (practicable) choice and it'll be hunting season for the big and powerful nations. We'll be caught with our trousers down and we'll end up screwed by one of them. Given the choice I'd rather the EU. At least their worker rights and food laws are worth having. But the tories will salivate at the prospects of US employment law and privatising the NHS to US firms and that will be that. I am most depressed at the prospect.