An sincere apology to a previous reader, how we can be extremely insensitive without meaning to be and, perhaps, a lesson learnt

I have one follower who has come out and declared herself. You will see a link to her blogs to the right of these words. I also have another follower who is a little more in the shadows, who professes, I can only accept sincerely, to be baffled by the kind of technology which makes a blog such as this possible, and who, thus, does not have his own blog.
Until a few days ago, I did have a third reader, who also declared herself to be a follower, and there was also a link to her blog to the right. It has now, however, disappeared. And I fear I have inadvertently upset her. I shall go on to explain how it might have happened, but before I go any further I shall ask her to forgive me - she will know I am addressing her - and I shall ask her to accept that there might have been a misunderstanding. If I am right and offence was taken, it was not due to oversensitivity on her part. If anything, it was down to a certain tactlessness on mine.
Some readers might know, because I mentioned as much in this blog when I was writing from Ibiza, that while I was on holiday, I came across by chance a copy of A People’s History Of The United States by a very respected historian called Howard Zinn. The purpose of his history was that it should serve as an antidote to other histories of America which told the story of the nation, so to speak, top down. He wanted to tell the history through the stories tribulations of the ordinary man and woman - the indentured servants who were all too often treated as no more than white slaves, the black slaves themselves, the native Americans, the immigrants who were played off against each other to compete for scarce work. I learnt a great deal from that book.
I was aware, in broad outline, of the history of slavery in America, but I did not know much of the detail. And while reading the book I came to realise what a horrifying, unspeakably evil detail it was and is. And I feel - I hope - that perhaps I understand a little better the deep sensitivity of Afro-Americans in matters of colour and their existence, and the reality of their lives both past and present. But it seems that I touched upon that sensitivity rather roughly, although inadvertently, in a previous entry to this blog, and for that I am truly sorry indeed. It was sincerely unintended. I think the reader concerned will know what I am talking about, so I don’t feel there is a need to be more explicit as this entry is almost entirely intended for her eyes only. From what I gathered from looking at this particular reader’s blog, she is wholly or partly of Afro-American descent and from what she writes on her blog very aware of the past lives of her forefathers and foremothers. The chances are that she has already given up on reading this blog, but if she does occasionally take a look, I hope she reads this and accepts my apologies.