Update

I generally agree.
I still recall all the hell you and H had to go through and having your DD with special needs, warrants some consideration to her and you as well.
SD is from what I understand a bit of a spoilt brat. She can have her father, but doesn’t have to take it out on you.
Having lived with my father overseas I understand that she could feel left out. He divorced his ex, but not his daughter.
My father actually deserted me (also my sister, but not so much) for quite a few years and my stepmother did not have any experience with children when she married him. Only later when they had my brother did she begin to understand the bond between a parent and child. It wasn’t always easy and least of all pleasant. I did feel like he left me, didn’t love me or respect me. I keep the relationship going, so did he to some extent. Lately he has issues with dementia and I know it could be over anytime.
My stepmother is nice, but I am not her DD. She has her hands full, her priorities.

So coming from all the experience of being an SD and a stepmother, I understand both points.
I hope you can establish your position with H to the fullest extent, but just know that he has a daughter who is not willing to give up on her father. Why would she.
She acts like he owes her. Entitled, not as nice and that is so uncalled for.
If she goes too far as far as you are concerned than you must call her out.
My father wanted my stepmother to go along every time.
All we wanted is to have him to ourselves if just for a few hours. I think she understood that and was fine with it, but my father never really tried. It was just easier for him if she went along. And that hurt. It’s almost over now, he has issues with dementia.

Let SD be close to her father, maybe even tell her they should spend some time together alone.
Being mean to your DD is a character flaw. That is in my opinion on another level. She should know better and her father should make sure she understands the situation.

She will always be a part of your family, but you can also just let them spend time together alone. Abusing you and being unkind is completely wrong.
In the end things work out somehow and time passes way too fast, so embrace the good times and forget the bad. It’s just suffering going through everything that went wrong.
Vent on here, but shake it off in your life. You don’t need more stress, you have your life to live.
I think you should simply accept SD has her own issues and being nasty is one of them. You don’t have to like her. It’s ok if you are slightly indifferent. It’s preserving your energy.
Life will teach SD humility. Marriage is not easy and once she will have children, her focus will be on her family.

I don’t know her, but I can tell you are having a difficult time and that says a lot.

Thank you both for sharing your perspectives they reflect a lot of strength and wisdom. It’s not easy to stay neutral and protect our own peace in such situations, but it sounds like you both found a balanced way to navigate this dynamic over time.
Maya, I'm so sorry to hear your father has dementia, that must be so difficult
The children have left now and upon reflection it wasn't too bad.
It's just the one thing that sticks with me at present was the lack of respect in our home. I did speak to H about this and I was surprised that he actually felt the same way. SD and her boyfriend would get out of bed and lie bare foot across the length of the sofa. I felt like saying, if you are tired, go back to bed. also the mess that they made was off the scale. Now H never speaks badly of anyone so when he said to me, that it's the way SD has been brought up, this was a dig at his ex wife, very satisfying to hear . I can only imagine the mess that they must make in their own home.
I understand that SD is in her parent dads house, but her boyfriend also lying across the length of my sofa in a practical strangers house, I found that extremely rude personally. I would never do that and I wouldn't have done it at that age in someone else's house. There was no where for me to sit. And dirty feet on the arms of my sofa? No. Next time I must lay down some boundaries.

Oh one other thing, there wasn't a word of thanks from SD and the boyfriend for putting them up in our house for a month. Not one single word of gratitude or appreciation!