I'm a mum to teen DS, who at some point during divorce got manipulated by ex and refused to see me. We now have a court order in place and I see him a couple of hrs every fortnight. But I still can't get over what happened, I'm traumatised by it, miss him so much, the life has never been the same ever since. Doing my best for it not affect daily life.
Went on holiday recently with a partner of 2 years and his DD (DS refuses to know them) She is lovely, I treat her as my own but she recently started to be cheeky, competitive and trying to get between me and her dad. At the holiday I let her sit in the front passenger seat a few times (she asked), I thought it is nice thing to do. But then when she wanted it again I said no. It was all nice and gently. She got upset and said she isn't here to argue with me and asked dad to tell me something. Her dad teamed up with her laughing at me, telling her how childish I am, how unreasonable, how I have disappointed both of them because I won't let her do what she wants. He then said I'm taking out on her because I have a bad day due to my DS not being there. I burst in tears. It wasn't anywhere near true. Yes I miss DS, but that's nothing to do with me not wanting to seat in the back of the car for his DD.
I felt attacked, he repeated it over and over again. I'm so hurt, feeling he used what I have been through to punish me for not doing what they both wanted me to do.
I feel betrayed. I trusted him so much. We talked about it and he said he has done that because I have attacked his daughter and I have broken his heart for refusing her to sit in the front whenever she wanted. But I haven't, I have only had a different opinion from her and said just that, nicely and gently 
He very well knows how many sleepless nights I have been trough because of DS, how many times I've cried, how abusive my ex is and how traumatic it was.
Am I over reacting? Do I see it wrong? I'm so sad.