Relationships: Ex-Strife

My stepdaughters are constantly with their nanny at their mom's house. I know I am not completely innocent because I do have the nanny watch them when I have to go to the supermarket or someplace where I know they would be miserable. But I told my husband's ex-wife that I would watch them during the day (take them to museums, the movies, shopping, etc.) to have them with my daughters more. But she despises me and said they are not my daughters and not my responsibility. This really insulted me because I have been married to their father for four years (since the youngest was 2 years old).

I am trying to bond with the girls since I am pregnant with their new siblings. I am just trying to make things easier for her and help out. I am VERY pregnant so maybe I am just hormonal, but I am really insulted by this woman. She is making me so mad—while I try to be nice, she is nothing but mean, saying "don't you have your own kids? Why do you want mine!?!"