@bigmike43,
Stop snooping in her phone. It was wrong and you were an insecure jerk to do so.
Was she 'emotionally cheating'? God, I hate that term. FFS, no. She was trying to get rid of the guy.
Go beyond this. It's tiny and not worth going nuts over, and clean the gutters or something if you're bored, rather than invade her privacy and confront her over someone who meant nothing to her then and still doesn't.