Re: Can't we get rid of May?
I've already done a longer reply. But the basic answer to the question " why didn't the Remainers mount a larger or at least equivalent campaign to present their views?" is that the referendum was triggered by those with a passionate view point, who had been actively building up support for years.
1) Your post souns rather defeatist, and sounds more like the Remainers simply weren't as passionate about remaining as the Brexiters were about leaving. You didn't have it in you to build a better campaign to show up the things that you believed to be lies (rightly or wrongly, I make no comment on that!)
2) You basically describe Brexit as starting from a small group who pushed their views until they got their way. There's your answer if you wish to remain in or later re-join the EU. In fact if Brexit turns out to be a really bad idea, you'll have an easier time convincing people to re-join.
3) Make the most of it. Good or bad, Brexit will probably happen. You can either live sad or live happy, you don't have to let this ruin your life. Adapt, and live well. It's not always easy but it can be done.
FTR I am slightly pro-Brexit. If I lived in the UK I would've spent a lot of time reading before voting, seeking material from both sides (especially from the Remain side - I try to read as much of the other's arguments). I could well have voted stay. I am very much anti minimum numbers in voting systems (aside from a simple majority, if 350,000,001 of 700,000,000 votes is a winning majority for me, as is the highest number of votes cast - I don't like FPP systems where 20% of the vote could win the election BUT if voting in such a system I support the result while advocating for change for next time)