Mrs Clinton is not the worst thing that can happen. The scenario you present is the only line in the sand that most Americans will not allow to be crossed, we argue and fret over all other possible ones to the point that we do nothing.
The people who wish for the destruction of this country were very shrewd in pushing our current President over her, because they knew that the woman or womyn voting block was not monolithic enough to ignore her politics should it be judged necessary to remove her through any means whatsoever (the gamut running from Johnson to Nixson to Kennedy). As it is, he has done more damage to our rule of law, infrastructure, military, industry... than any deposed president ever dreamed of, but the merest peep against him threatens to divide the nation on grounds other than ideology.
We have been paralyzed by the fear of the destruction that would ensue by either choosing to allow him to push his agenda, or choosing to stop it - a much worse outcome than the “Stop Hillary Express” or “Operation Chaos” folks contemplated. For my additional two cents worth, lawfully removing him at this point is probably less destruction than allowing him to remain, if it is not too late.
Romney would have merely moved (and assisted) the start date of an inevitable conflict to the next generation, which would be less likely to succeed than ours, if it even noticed something was wrong.
Shocked as I have been in some ways at the rapidity of change in the last seven years, I still stand behind my not voting for him. Doing so would have been kicking the can down the road to my children, while allowing their every chance of defense to be destroyed along the way.