She usually doesn't like anything on fb, not even my pics. But recently I see her liking this new guy's pics, even old pics from 2-3 years ago. She met him a few days ago in class. She said they're just friends but I suspect otherwise. I need a stalking app to find out the truth.
Nope, no such app that I heard of. Maybe you can try looking around in Chrome extensions? Worse case scenario is just stay online all the time on your computer and see your friend's activities on the sidebar :/
Dude you sound really insecure. If you feel you can't trust her you don't need to be together. People need to realize just bc you're in a relationship doesn't mean you cut off the opposite sex. So what she made a friend? you're on a path to becoming very controlling I can see it.