If you are forced to engage in conversation with her, remember to keep it brief. She doesn't deserve your time and hopefully, there are other surrounding friends to chat with other than her. Also, don't completely ignore her. It's childish and shows you're still affected by her. Don't be overly friendly either. All she deserves is a friendly wave from across the bar. Nothing more than that. Don't forget -- she isn't in your life anymore, so why would she need anything more than a wave?Don't overcompensate. Don't try too hard to flirt with girls you see just for the sake of developing jealously. Most likely, she doesn't care anyway. If she shows up with a new guy, don't show any sign of emotion. She's in the past. Whoever she dates is none of your business. If she's already in the past, there's somewhere else better out there for you .......you probably hear that a lot but it's true.