Anyhow, once I realized that she was going to be a long-term part of my ex's life is when I stopped being mad about the inevitable. My son called her on mothers day to wish her a good day. My son calls her mom when he is at their home. She is super involved and my choices were to either be bitter about it thus trying to make her and ex miserable which would then make my son miserable or to deal with it in an adult manner so my son didn't feel out of place at either home. My son is more important to me then trying to oust her.
Amen Sister, Amen.
There are many of us "Steps" that want nothing more, regardless of the genesis of the relationship.