This must always be there to some degree, but it is now, in the UK certainly, and from what you tell me, in the USA also, accelerating towards a serious crisis. And then hatred that lasts for generations. It would be profoundly naive to imagine that it 'couldn't happen here' - wherever 'here' might be. Granted, such extremities might well not be imminent, but both our countries are heading in that direction beyond any doubt. This is not good.
History is full of such examples.
How the present sorry situation has come about is doubtless interesting but not particularly relevant. We are where we are and we must play the cards we are dealt. The answer, of course, is, 'a bad one'. Be it insecure, incompetent or just downright sinister it is not remotely fit for office and should change its ways or go. No one starts a big fire or a big business - they start small ones which grow.