From what I saw, when Martin Brunt confronted Brenda Leyland she was going shopping with a friend. Why do you naturally assume that she was a sad and lonely person simply because she did not believe the McCanns? Maybe you want to believe otherwise but I think that the McCanns were behind this troll dossier. They are capable since they have already tried to destroy Gonçalo Amaral in everyway possible, IMO and they'll stop at nothing in their quest to silence anyone from saying anything negative about them.
I think you have the chain of cause and effect the wrong way.
Amaral tried to destroy the McCanns.
The McCanns were resilient enough to stand up to him and strike back. As a result, it looks as if Amaral might end up being the one destroyed.
No joy in that, just a natural consequence of the chain of cause and effect.
I fear Amaral may get a consolation "prize" though.
The McCanns and Madeleine's brother and sister may just never know what happened to Madeleine ...