Best way to get back at an Ex Girlfriend

Get over it and move on! Exes are exes for a reason. You should work on improving yourself at this time(Get new hobbies, learn to dance). You are not in an emotional state to try to get back with an ex. Take your time, work on improving yourself and maybe in the future something will come of it but don't expect it. Trust me, there is someone better out there for you.