Why do you think Judy cheated on Tom?
Its clear Neil did it for lust and thought it would be an affair without consequences but Judy ?
I imagine she did it because she felt abandoned. Tom was a guy who went often to Hunting trips leaving her slone and actually when he meets with his son didn't seem to loving.
I could also guess he was a violent husband, otherwise he wouldn't have come up with such an evil plan of revenge.
He would have planned something harmless to make Neil suffer a bitt but his plan was something that only an evil person could come up with.
I wished they have let us see why Judy cheated on Tom and that way truly see both sides of the stories the cheaters and the ones who were cheated on.