Okay, so I've got a major mother issue. PLEASE HELP! ?

So, in June I got married, and with the marraige, I gained a new step-daughter along with my husband. I absolutely love Adelia, but her mother is another story. She absolutely hates me; she constantly tells me what i'm doing wrong, picks Adelia up when it's not time yet (we get her weekends, fridays and every other wednesday) and she is incredibly rude whenever I pick adelia up or call her on the phone (ie; shutting the door in my face, "accidently" hanging up on me, etc) And recently, she told Adelia that I didn't care about her. Which pissed me off. I love Adelia to death; as far as i'm concerned, she is my daughter, just as my son is my son. Maybe she isn't by blood, but that makes no difference. I love her unconditionally, and it irks me what her mom is doing. HELP!