Wyn,
It is simple, times have changed. The Monarchy is constantly evolving and adapting to times of change. In the 1930's, divorce was a scandal. In fact it practically required an Act of Parliament to disolve marriages. If Edward VIII had intended to marry a black woman, that too would have created a constitutional crisis and would most certainly have ended with his abdication. Similarly, if Edward VIII had been gay, he would still have had to have abdicated. As Stanley Baldwin once said "You are not a man sir, you are the King. In the choice of a Queen the voice of the people MUST and WILL be heard".
The official stance on the matter is that Camilla will not be Queen. However this is unlikely ever to actually take place. The reason being, it would require an Act of Parliament to change her official postion from Queen to Princess Consort and this could only take place after Charles becomes King as no Queen Consort currently exists. Therefore when the Queen dies, she will automatically be Queen and she would automatically become Queen in the sixteen other realms and territories beyond the seas. It would require an Act of Parliament in all of those countries to deprive her of the title of Queen. It would be a bit silly to announce the couple as TM The King of the UK and the Queen of Canada. Rediculous!
I was a little struck by your reference to Camilla being a former adulteress and divorcee, it did seem rather harsh. The reason I say this is because there is nothing wrong with being divorced, if the marriage simply didn't work out. Okay.. I concede that Charles and Camilla did a bit of a dirty trick on Diana and she shouldn't have been used in that way, but Diana was just as bad, its just because she was pretty and nicey nice that everyone feels that they can forgive her.
Let's not forget Diana's involvement in the Carling marriage. Diana herself had an affair with Will Carling. Julia Carling thought that her marriage was very happy and idolized her husband, in fact she worshipped the ground that he walked on. Next thing you know Diana comes on the scene and she and Will are having an affair. Julia's world was shattered and she filed for a divorce (good for her!). Diana destroyed the Carling marriage and it was she who was the "other woman" in that marriage. It doesn't matter that she was unhappy in her own marriage, she should have known better, because she knew what it was like to have someone else sleeping with her spouse.
Hypothetically, if Charles and Diana had managed to save their marriage, Diana herself would have been a former adulteress (the destruction of the Carling marriage!) and she too would have become Queen.