I don't know that Trump will really have that much trouble with the rest of the world at a G20 summit (possibly protectionism though I wouldn't count on him for fighting reliably for that if that is what one wanted, possibly climate change). Mostly Trump may be a disaster for the poor citizens of the U.S., but frankly that really isn't a problem the rest of the world cares about, that is problem of the poor people living here. The rest of the world may care about trade and to a lesser extent about climate change (well of course money comes first).
Bill Clinton hmm, it's a different kind of disaster than Trump, Bill Clinton actually understood politics and much about the world, which doesn't mean all his policies were good, merely that he wasn't completely clueless. And so he had that going for him even with Lewinsky.
As for Lewinsky, basically all relationships with such an extreme power imbalance are somewhat exploitative (and no it's not the less powerful person's (Lewinsky's) fault). Extreme age differences like that where one person is still quite young, and the other much older, are almost always exploitative in a way (plus an intern and the president, talk about a power imbalance). So no it's not Lewinsky with the power, and yes it is a rather screwed up situation, but what can you do, it's legal and they are adults, and it might also be cruel to Hillary (duh, cheating on one's wife isn't usually being a good husband unless it's an open marriage) but neither did she divorce him.