OP, she sounds spoiled, entitled and selfish.
She is manipulative and knows well how to pull your strings.
She has lived out of home, messed up by being used, and is now wanting to dictate your life.
Really really selfish.
You are doing her no favours. She will not grow if she's babied. She will not mature if your relationship breaks up.
She will just hunker down on being a more selfish adult that expects everything to go her own way.
How dare she think that she somehow doesn't have to share the load.
Appalling selfishness.
YOU are at fault here and you really need to own it with actions not words.
YOU did not have affairs.
YOU did leave your children and not bother.
YOU have not decided to abandon your children.
YOU are the parent that has been there for them.
Stop with the useless guilt that is NOT yours.
Take responsibility for your shit, not that of their father.
That is all on HIM, not you.
We cannot be dictated to by guilt for the choices of others.
She needs one decent parent and you are it.
Stop allowing her to be a selfish manipulative lazy madam.
Take her aside and give her a real zero tolerance chat.
Tell her YOU are sick of her manipulative selfish lazy bullshit. That she either starts to sort herself out or she needs to find a room somewhere.
Do not sell your house so that she becomes even more controlling of your life.
I actually think that she is very very controlling and you need to watch this very carefully.
Do you want to be her carer for life because she has regressed?
As for your other daughters?
They are telling you that you are in the wrong but you continue to favour her?
You need to really look at things from their point of view, .......how you and her and this toxic control she has of you,...... because of YOUR guilt, could upend THEIR lives.
There needs to be a complete reset where you tell her you are sick of her and her bullshit.
She either cops on or she leaves.
You won't be leaving, she will.
You need to find your anger.
Your other daughters will rightly feel huge anger towards you for your failings to protect them from their sisters selfishness.
I would think you need to be a lot less pleasant and available to your eldest.
She badly needs consequences and to see that you are fed up, pissed off, and have had enough of her bullshit.
Keep saying get a room elsewhere if this house is not to your satisfaction.
Tell her that SHE messed up and you have offered her a space to live.
Her thanks is to sour it.
Enough is enough.
Shape up or move out is what she needs to be told.
25 and thinking she rules the house?
If it was a son I would tell you that you were in an abusive relationship.
Think about that.
Because it applies here.
She doesn't get to control your life, home and that of her sisters.
Go back to your partner and tell him that YOU take responsibility for being manipulated by her and that she has been told to shape up or ship out.
Normally I would say this is a man issue but you need to see that your daughters have told you that you are unfair.
YOU need to change.
She WILL respond to you changing.
Self interest will make her respond to your change of attitude towards her.
Don't be manipulated by tears from her.
She needs to see you hard, fed up, and done with her bullshit.
All families bicker.
Families become toxic when one person is allowed to dictate too much.
I know this because I have lived it with a 24 year old.
She needs firmly putting in her place and told you work with the family or you leave.
That simple.
"No one member of this family gets to dictate its happiness. You aren't happy with the rules etc.,? Move our and live how you want elsewhere, but you will not behave like this any longer in MY home".
She thinks she is your boss.
Big mistake.
Hope the above gives you food for thought.
You are not alone.
This is a common situation with adult children and unless you handle it firmly, it will only get worse.
Oh and one last thing. If you move out and rent with your daughters, she will only get a lot worse, will do nothing and have proof that it IS her that is top dog in your life.
Screw that.