This is quite a stretch, to claim that Facebook actually had any effect on the election. In fact, part of your premise is quite wrong — that all fake news was anti-Hillary or pro-Trump, when in fact there is plenty of fake news that went the other way. Just today I came across a fake news story claiming that Trump lost support of the police union after saying Tulsa shooting cop “choked”, a false story published in September.
So those fake stories can be seen, if anything, as a wash.
That said, I think it’s important to criticize Zuckerberg, and there is plenty to critique. My advice to him would be to shut down Facebook, resign from tech, give most of his money to charity, and go live in a cabin in Montana.