What has happened has happened. The EU is not an organisation where you 'put one foot in, you take one foot out, you put one foot in and shake it all about'
We had a referendum and like it or not ( and I don't like it) the result was that we came out of the EU. Wasting time and effort now bemoaning the fact and whinging left right and centre will get us not just nowhere, but up a creek without a paddle.
What we need to do now is work to get good relations with the EU and work out treaties and agreements that mean we have as goo an entry into EU markets as is possible, as, of course. we will be doing with other countries.
However I think priority should be given to regularising our relationship with the EU. They are our nearest and one of our biggest markets. In addition the change of President in the US has majorly changed our relationship with that country.
It is clear that the negotiation tactics of the Trump adminstration consist of saying to their 'partners 'do everything my way or I will hit you on the head with a big stick and kick you up the bum.'
Existing treaties are not worth the paper they are written on. For the foreseable future I can see no way that we can sensible negotiaate with the US on anything. This makes our links with the EU even more important to us, for every reason from trade, to being associated with a larger international organisation when Trump starts waving his big stick.