How do you get over an Ex?

-I can't seem to get over my ex. Its been two years and she is on with her second boyfriend after me. Crazy thing is everytime she is not with someone she is more friendly and wants to be friends, hangs out at my house with our child (this then seems to mess with my feelings) and then she finds someone else and she doesn't come over anymore...obviously because she has someone else but why is she doing this in the first place. Then she calls me like every single day to talk about either the past court case or relationship or our son. Why does she have to call every day...is this a game? What steps should I take...Tell her to only call you about your son. Give yourself a day to just cry and realize that you're better without her.