I don't think there's anything wrong with occasionally showing one's emotions to a wayward spouse. I think the danger comes when either:
a) the betrayed spouse then makes major DECISIONS based on their emotions; or
b) the betrayed spouse looks to their betrayer -- the wayward spouse -- to SOOTHE them.
Starsky
I know you're hurting right now, mdu, b/c of your dad (and I'm very sorry about that). But you would be wise to keep the above advice I had given you in mind.