Current dilemma:  A couple days ago, my fiance called his ex back because she was questioning why she has to pay for a portion of her daughters medical bills...because she agreed to according to the current divorce decree, even though she claims she had no idea that was the case.  Although we know that is a lie because he has had this conversation with her many times before.  (SD has had several health issues and her dad carries the only insurance on her).  He put the call on speaker (without ex knowing).  Ex is super narcissistic, self centered and in my opinion, a terrible mom.  She has always been manipulative in regards to both of her kids and their dad.  She has by far treated the kids differently, at times hitting or verbally abusing her son but bending over backwards to keep her daughter "happy".  Of course my disdain for the ex is unfortunately sometimes obvious...I am not a fake person.  After the phone conversation was over, my fiance and I discussed what Ex had said and how she was trying to manipulate the situation again.  SD was also there for the phone conversation and afterwards.  SD then completely blew up on both of us but primarily me, accusing me of trying to screw her mom over.  SD then told her dad that he loves me more than her, and she left and spent the night at grandmas.  SD is 19.  I have been with her dad for almost 10 years, engaged for the past 2.  

Throughout the time I have been with my fiance, I have experienced outbursts from SD.  My experience tells me, when she doesn't like what she hears, isn't getting her way, or wants attention, she throws a complete temper tantrum!  I really thought that she would eventually grow out of it, but as she gets older, it almost seems to be getting worse?  Of course due to the limited time in the past, her dad had seen her, he typically gave in as to keep the peace and would often make excuses for her behavior, "its because of her mom!"  Recently, I have been very proud of him...he has listened to my advice about not giving in to her because regardless of WHY SD does what she does, SHE has to take responsibility for her own actions.  He has not given in for the past couple months, and it has been working, until  this most recent outburst.  Now he wants me to apoligize in order to "smooth things over".  I am afraid that she is trying to drive a wedge between him and I and push him to choose me or her... 

I honestly feel that I have treated his kids very well throughout the years(he has 2, son 22, daugher 19). I have worked at least 2 jobs, at times 3 jobs to pay off my own student loans, but to also make our situation better, as a family.  Ive never asked for anything in return except for appreciation and acknowledgement.   By no means am I perfect but I have tried to learn from my mistakes.  I love my fiance am willing to do almost anything to keep him happy and our family together...with that being said, I refuse to be used in some sick game that I believe SD is trying to play!!!

PLEASE HELP