Is this just my insecurity?

I am a 38 year old divorced female in a relationship with a separated 33 year old man. We both have children from our previous relationships and it is pertinent that communication with our ex- spouses stay open and positive to facilitate co-parenting int he most effective way possible for the benefit of all the children involved. We are having frequent conflicts over this communication and its beginning to feel like we are at an dead-end. My communication with my childrens' father is frequent and very light-hearted but limited issues specific to the children. His ex is quite different and therein lies the conflict. Their relationship is much more futile and emotional and bitter. She text messages him multiple times a day and calls multiple times a day as well. Her calls usually have nothing to do with the child and say things like "OMG look so hot tonight! you should come and have a drink with me" She has proven herself to be a very manipulative person who I have caught multiple times in lies to try to compromise all kinds of relationships. She is very threatened by the our relationship and constantly tries to use her child as a weapon the manipulate this man. She technically does not even have custody of the child herself (her parental rights were terminated by the court for all 3 of her children) and her grandmother raises the child but tries to act like "supermom" I feel her contact is in appropriate and disrespectful to both him and myself and the relationship we have. She infuriates us both with her attitude and spitefulness yet no matter he does these texts and calls persist. I fear that he is doing something to encourage her that I don't see. I doesn't add up to me that she would persist knowing how he clearly feels about me. He insists that she is just bitter and trying to cause problems and I should not let her get to me.