Caught between a rock and a hard place...

My oldest has Aspergers and this divorce has been really difficult for her because she tends to see everything in black and white and has a harddd, if not impossible time, just trying to be neutral like her younger sister can do. They are not happy that their dad cheated and began this whole divorce process. they are not happy that they have to go stay with him and his young girlfriend, but they cope. My stbx embarassed my oldest daughter in December, when people she knew(in a choir) thought the gf was me. The biggest thing though, is that although I think she would actually visit her father with her sisters sometimes, he threatens not to drive her to school, etc if she doesn't come, so then she gets mad that he is "forcing" the relationship. I completely agree with her. At 19 she doesn't have to see him at all but as a special needs person she really would like to have her "old dad" as she puts it, back in her life. She finally has a small group of friends which she socializes with- which is great for her self-esteem and happiness, so she wasn't seeing her father much and he got mad about it. Now she is angry back, but offered to talk withhim with her therapist. He won't agree to that because he thinks the therapist is an idiot. He wants to talk alone with her, but she is afraid of that. I understand, because stbx is a master manipulator of the English language. Even I, an educated adult, could never out-talk him. I don't know what to do. Stbx blames me for everything. Daughter is now saying she wants to cut off "forever" but I don't think that is what she REALLY wants. One of her sisters is now upset with both of us for "not moving on" and why do we keep giving dad a hard time? ( her coping style is to socialize casually with dad and gf and never talk about anything serious- what she really feels anymore- because it won't do any good)I want my oldest daughter to have a real relationship with her father, but on her terms, not his. The only idea I thought of that might work is if they talk with their nephew/cousin present -( he is in his 30's) who loves them both and is trying to remain as neutral as possible with both me and my stbx. Advice? Stbx is a master at making me feel like you know what, but won't admit that it is normal for his daughter to still have mixed feelings about him and this new lifestyle/family change. I am having such difficulty with this. I also recently found out that one more thing stbx was lying about was the woman's age. She is only about 10 years older than my daughter and 22 years younger than him. It makes me feel so odd. It also makes me think that someone that young might still want babies of her own. My head is whirling. Would she want them with a 52 year old barely employed man(she works f/t but doesn't earn much) or will she decide down the road that he was not such a great catch after all and leave him? Would they actually start another family when he is only givng me $250/mo now for the younger two? My feelings are so mixed up , too. Some days I am really almost thankful that the girl chased him. I don't want to be married to him anymore- for any reason and I realize that, but the trauma to my daughters, the tension in the house, the blow to my financial security- it all makes me so angry...and- he keeps making more changes to the marriage settlement and I want it done...Advice?