Er ... no we haven't!
We have activated divorce proceedings and all that can happen now is that we
LEAVE the EU. I refer you to ...
http://www.lisbon-treaty.org/wcm/th.../title-6-final-provisions/137-article-50.html
... which states ...
"3. The Treaties shall cease to apply to the State in question
from the date of entry into force of the withdrawal agreement or, failing that,
two years after the notification referred to in paragraph 2, unless the
European Council, in agreement with the Member State concerned,
unanimously decides to extend this period."
... which means that the divorce can be delayed but
NOT stopped.
So, the UK activated Article 50 but now the "Leavers" want to change their mind so I again refer you to Article 50 which states ...
"5. If a State which has withdrawn from the Union asks to rejoin,
its request shall be subject to the procedure referred to in Article 49."
... and Article 49 ...
http://www.lisbon-treaty.org/wcm/th.../title-6-final-provisions/136-article-49.html
... is for
ANY country that wishes to join the EU.
So, in accordance with Section 5 of Article 50, the UK would be treated just like any other candidate for membership; except that by now the UK may encounter an enormous amount of animosity from the other members.
For most people who voted "Leave" I can only quote the well known saying ...
"Please Lord forgive them for they know not what they do."
Rather than defending their vote, it would be much more sensible if the people who voted "Leave" admitted that they were mistaken because they were not informed of:
o The procedures involved in leaving the EU.
o The impact that such an action would have on the general public of the UK.