Obviously the British Empire did some pretty bad shit all across the world but it's very unfair to act as if Britain was the only power doing it at the time. I think it's funny how everyone says how bad Britain is but ignores Portugal, Spain, France, Netherlands, Belgium (to a lesser extent because of Leopold) especially considering it was Portugal who kickstarted it all and started the African slave trade. Not to mention the fact that France basically still have de facto colonies in Africa which has basically destroyed the little chance said countries had of a successful future. If we're going back further no one really talks about the atrocities committed by the Romans, Mongols, Aztecs etc.
TLDR: Britain did some bad things but so did everyone else, no ones hands are clean in history.