And the fights continue

Last night Twin and I get the following text from Big Sis
There seems to be a divide appearing within our family, mum and me versus you and dad.  It used to be that the 3 of us kept our neutrality between our parents but no longer it seems and this makes me sad (note Big Sis only remained neutral when it suited her ends and she would always try to force us to take her or Mums side when it suited)I could give a hundred examples of why I think this but I will keep it to a few.  Dad's assessment of mum seems to be the one you have most sympathy rather than mine.  Dad's attempt to exclude myself and smallest child from niece and nephew seem to include you.  I am sure you will say it has nothing to so with you but you are clearly happy to have conversations with dad which include information that is extremely important to me but you tell me nothing about it (not my place they should talk to each other). The most recent Florida farcial nonsense being one (didn't it occur to either of you just how much risk that would put my children at, you grew up with our father as well!!!)
I know that you both feel that my problem is with Dad and that both of you should remain neutral but I feel completely betrayed by your silences.  I honestly hope that I can appeal to you to be forthcoming with me in future and prevent this divide becoming a permanent situation.
My response was as follows - The assessment I have of  Mum is based on my experiences with her and no one elses.  Before the fight we spent more time with her and had a better idea of what she is like in person as opposed to how she presents to others.  As for Dad while I agree he was a nightmare when we were growing up he has changed and I don't think he is as bad as you think, however I know you don't agree so we will have to differ.  If i ever thought he was treating those kids badly I would be the first to step in and stop him.  The fact that you both can't communicate is not my problem and I am hurt that you think I need to act as a spy and report back on what he says about the kids just because you are both to bloody stubborn to talk to each other.  I am not doing it and I will not be made to feel guilty about it.  I am not trying to cause a divide between us and I hope you can see my side.
Big Sis responds by ignoring most of the text and just asking why I think dad has changed.
I explain my reasons which she totally ignores and states her case and why she thinks her kids are in danger.  I refrain from saying they are more in danger from her than him.  She then states that dad has not changed, that the kids are only objects to him (not true, Big sis treats them more like possessions than he does) .  She says dad is manipulative and conniving.  Also not true, it is Big Sis who is extremely manipulative.  He has no empathy - actually Dad has empathy but he does have no sympathy with Big Sis.  He cannot forgive her for her behaviour when she was drinking and how she neglected and abandoned her own children.  She says he is selfish - when it comes to those kids I do agree he wants to spend time with them and make sure they get to spend time with their friends and he selfishly guards their time so they can do that.  Then she says that I idolise him.
I respond by saying that her judgement is clouded by our childhood and how we had to treat her when she was drinking ( she is still very resentful that we didn't just pander to her and that we made the kids a priority over her).  I say I don't think that I am going to change her mind but that I will not be made to feel guilty or be abused just because I don't agree with her.
She then says that basically she is right and that Twin and I aren't acting like adults about this and that she hasn't abused me and that I am not to talk to Dad about it.
I respond by saying I hadn't planned to talk to dad bout it and that I am acting like an adult .  I also say that just because I don't agree with her accusing me of not being an adult and idolising dad is abuse to me  and that it also doesn't mean I don't see the situation.
Big Sis says she was simply explaining her point of view (not!) and she was only asking me to put myself in her place.  I say she is not simply stating her opinion, that she is accusing me of not being an adult  and of idolising dad.  That she is not willing to listen to anyone elses opinion unless they agree 100% with her and that I don't want to talk about it.  She then says that accusing me of stuff is not emotional abuse (yes it is!)  and what was my point of view ( I think I already stated it).  She then says she doesn't want me to spy and then asks me to spy to protect her children's safety and then says that it is me that is ignoring her point of view.
I reply that I do see hers but my original points still stand.  That she hasn't listened to me she has just ignored it and said I was blinkered and not acting like an adult because I don't agree with her . I agree that the kids safety is the most important thing but I truly don't believe they are in any danger.  I say that I am not talking about it any more as its turning into a major fight and we should just drop it.
She replies by saying the well being and safety and emotional health of my children is a priority of ex husband and myself ( She finally remembers the children's other parent who is happy for Dad to see them and has raised no concerns, and since this is the parent they live with I think we need to take his views into account) .  I hope you never find yourself in the position our father put me in (nope because I don't plan to have any kids and I am not an alcoholic who repeatedly put my kids in danger). She then says she is not asking  me to spy and then asks me to spy again.  I only hope you could respect my position  as their mother over someone who has already royally f***ed up their own children. Good night
This just upsets me I mean I know Dad was a total nightmare and I know he contributed greatly to all our problems but so did mum and Big Sis just absolves her of guilt. Also Dad has changed but Big Sis is just so resentful about him that she can't see it and does tend to blow stuff up.  She also forgets that she has had a major part to play in the whole situation.
Poor Twin who has been having a reasonable conversation with Big Sis (because she hates confrontation and makes peace for an easy life - sorry Twin but its true) then has to put up with a major rant from me and I breakdown into tears.  She tries to fix it with Big Sis by telling her how upset I am and how I am worried she will try and stop me seeing the kids (which was the implication of the first email).  She does this without telling me and it actually makes me even more upset because I would not have asked her to do that but its too late and once I calm down and apologise to Twin, it seems a little better  The Big Sis sends me picture of littlest niece and I calm down some more.
However the situation between Big Sis and Dad is still ongoing and if Big Sis tries to make me take sides again I won't be backing down but I am unsure of what will happen next.
While I do sympathise with Big Sis I also understand where Dad is coming from and I think they both need to sort this out.  I would suggest they have some sort of relationship counselling if they weren't both so opposed to counselling of any sort.
The only saving grace is that Mum has so far stayed out of it and hasn't contacted either Twin or myself.