At the risk of opening all this up again, what is this "our history" of which you speak. There is the history of my personal ancestors which, generally speaking, I have been able to trace back to the 17th century. I can tell you I have no ancestors who got rich on the back of the industrial revolution and the growth of empire. I have people who dragged themselves up to working class, and in some instances lower middle class, on the back of the benefits of both, but none who were involved in decision-making that would make me feel remotely anxious about my personal history. I suspect you, as a proud Brit/Spaniard can also trace your ancestry back to the same period. Does your personal history have any ancestors who were actually responsible for events that we would now call atrocities? I doubt it.
So then there is History, with a capital h, as an amalgam of all the histories of our own personal ancestors. That includes all the empires that have come and gone, all the atrocities performed by the Sumerians, Assyrians, Egyptians, Romans (I could go on), and yes, the British, Spanish, French and Germans to name but a few. But that is as impersonal to me as it gets. I contributed in no way to it and, as far as I can make out with almost certainty, nor did any of my ancestors. It is interesting to study, sure. Lessons can be learned about how to behave, sure. But even leaving aside the contemporary contexts, in which, presumably, all these events, which we now consider atrocities, were considered to be normal behaviour until they weren't, I still have no personal feelings about any of it. Things happened, we now consider some of them bad. Done and dusted.
And this isn't revionist denialism. No-one, as far as I can see, is denying any of it happened. Revisionist denialism would be removing the boat from the city's heraldic achievement because of some tenuous link to an atrocity which the city's population made efforts, at some cost, to end.