No need to explain the neglect, we've all done it and that's not really the issue. It's mostly a clever excuse for bad behavior.
I don't think you have to snoop to determine if she's having an affair; I think her behavior at this point should give you the answer. It may well be an EA and maybe a PA, but in my opinion, someone other than you has her heart.
I'm hoping others provide input because I'm new to this stuff so I shouldn't be making definite statements.
Lastly, if your snooping will cost you your job, then certainly don't do it. It's not worth losing your job over snooping.
