This will probably be long. I would really appreciate some advice.
To start; I hold my hands up and admit I made some naive decisions.
I met my partner four years ago. He has three children and had been broken up with their mother for two years. We moved in together very quickly, more for logistical reasons than anything else. The children (teens) had no opportunity to get to know me nor me then.
We muddled along quite well for a while. Despite me not having children of my own I think I have a lot of empathy and patience. But we had not planned adequately and were trying to figure out things along the way. I never felt like a stepmum, just dad's girlfriend (which I was) and that was fine. The kids liked me even if they didn't like the situation.
His children are not easy and the breakup with their mother was appallingly acrimonious. I felt I played mediator a lot and felt worn out with it. His eldest two are now NC with him. He has tried therapy with them and got nowhere. They believe a lot of stuff which isn't true (I can say firsthand) and then there is a complicated emotional overhang from the marital breakup which I have lots of opinions on but I didn't know them then so it's purely speculation on my part.
He and I have a child of our own now. His youngest (she is now 14) does talk and visit but is very demanding, very rude and very self entitled.
I know life is not perfect for her but we truly try our best to give her a secure home, space of her own, time with her dad, sensitivity around the arrival of a new 'youngest'. I get it's been hard. I don't expect it to be all sunshine and rainbows.
But, it's not getting any better. She is horrible to our daughter, her sister. It's nearly three years now since the baby was born and she hasn't warmed to her at all. We cannot leave them alone at all as my DSD would not pick her up if she fell or communicate with her at all. Even leaving the room briefly I've overheard very harsh tellings off, stealing her baby sister's food. If I ever say something like "help her onto the seat, she's slipping" she will calmly remind me it was my choice to have a child and if I wasn't prepared to take responsibility for her I shouldn't have had her. I find this unusual wording for a teen and like she is repeating another adult's words.
My daughter adores her big sister, follows her around and if she got a hug (it has never ever happened) she would probably explode with excitement. I do insist my DSD says hello back to her but that is as far as it goes. She openly insults her. Thankfully as this stage my daughter doesn't seem too bothered but I've noticed she is getting shy about approaching her and will whisper to me to go and see her sister with her. My DSD never held her as a baby except when instructed to by her father and would hold her out away from her body in protest.
I really don't know what to do. I'm not sure what I'm looking for here. I've tried to talk to her. She simply says "it's fine" and shuts down.
The sad reality is I know I'm the adult in this situation but it is so hard to rise above it. I find it hard not to dislike her. She is very demanding, opinionated, critical in general and I find myself snapping at her or engaging in arguments which is frankly pathetic. I know she's young, I know she's trying to find her place in the new setup, I know she's been let down by adults and keen to protect herself.
I am just struggling so much. I'm so tired. I've been critically ill for a year and am in recovery but it's a long slow road. I buried a parent last year. His family are religious and traditional and do not approve of his second family so treat me like a second class citizen. None of his children or family sent me condolences or a get well message. Plus I feel like I put so much into the initial arrangement when all three stepkids were here and got horrendous abuse and treatment that I just wanna prioritise myself and my daughter now.