You have no problem keeping company with outed sociopaths?
I would argue that someone who murdered his wife because she cheated on him probably has poor impulse control. All other things being equal, I'd give the job to the person who hasn't taken a life.
That said, I'd also prefer the candidate with equal qualifications and no felony.
If a 'cheating spouse' is the worse you have to deal with you'll have lived a lucky or short life.
Death of loved ones, marriage break ups, losing jobs is life. Get over it. It happens to all of us, this me, me, me mentality that we live in a hollywood movie and just because theses things happen to us it's a world event gets a bit tiring.
Depending on your definition of "snap", this is unsubstantiated opinion, not a fact deserving the assertion you used.
It may be that everyone will "snap" if provoked enough if by "snap" you mean become aggressive, possibly entering into a fight, but even then you'll have to sell me that everyone is susceptible to this.
If you define "snap" as taking of another's life when there is no direct threat to your own (which is usually what we are talking about when discussing the murdering of a spouse), then I think you have a LOT of evidence you need to bring forth.
Unless the "non-felon" is simply smart enough that he hasn't been caught yet.
To be honest, though, it depends a heavily on what the person's crime was. Do I care that a guy got caught with a pound of weed? No. Do I care that he embezzled from his employer? Definitely. A guy who killed his cheating wife isn't a big concern, but I could never trust a guy who "snapped" and assaulted some random person.