You do nothing, kuz ur a man...u got balls.
just move on...no contact needed. any form of contact makes u look a fool. gives her more power as if shes all mighty and up there with the Palins. (political joke, name usage is unrelated to subject)
advice to all: do not try to make contact, her moving on was her signal to you already, nothing else needs to happen. she doesnt even owe you an explanation. you dont own her and she doesnt own you (even if married). any form of contact just starts a bad habit. you dont wanna start a bad habit. next girl comes along, you got this lil itch if something goes wrong...just 'learn' how to move on. life is easier that way.