Assuming Edwards keeps his affair a complete secret (which wouldn't have been that difficult, given everyone but the National Enquirer was ignoring it), it wouldn't have taken much opposition research for Trump to find out about Rielle Hunter. Of course, it's not like Trump would've been the best attack dog on the subject, with his multiple exes and divorces.
Former Senator John Edwards/Senator Kamala Harris 269 EV 50%
POTUS Donald Trump/VPOTUS Mike Pence 269 EV 49%
The House chooses Trump, the Senate chooses Pence.