I don't think there is a right or wrong application. She dumped you and is with another guy. What do you have to lose if you contact her or if you don't? Do what works for YOU. Eventually, pride steps in and you'll get over the urge to contact her.
Don't beat yourself up over it. Go in with the 'no apologies - no excuses' frame of mind. If she is bothered by the fact that you still care.....good. Maybe her guilt will ruin her day.