Step Mom Vs. Mom

I finally blow up on my husband's daughter mother after holding things in for almost 3 years. Then when I do I'm in the wrong when she has be littled my husband and myself. I'm just tired of fighting an endless battle. I'm tired of her acting like "mother of the year" when she has nothing to do with her daughter. I hope and pray my step daughter does not end up like her mother because her mother is a POS in my book but I would never be little her in front of her child for the simple fact no matter how horrible she is or how horrible she acts that's still my step daughters mother. I understand that I'm always gonna be looked over when I do everything and anything for that sweet girl. Out of all of the horrible things she has done the worst was when she would go out and party on Christmas eve with her bf and asked me to watch her 2 month old and to bet it all she's pregnant again . She puts up a fight for us to see my step daughter but yet when it comes to her other child she could careless how long I keep him. I understand God gives his hardest battles to his strongest solders but there is only so much a person can take. Rant over! please let me know your opinion about my situation and if you're in a similar situation. I posted anonymously because you never know how could come across this and had more fuel to the fire !