I'm curious.. has your SD gotten any counseling to deal with the fact that her mother isn't around?  I have a feeling that what you get from her isn't so much that she doesn't want YOU around personally.. but that she is having problems dealing with the fact that her own mother isn't there.. and she sees that as unfair in her universe?

I think that even though you say you don't want to be seen as being "mean".. you kind of are doing this in a way that you hope she sees what she is missing.. so I think in a small way you are hoping she feels some of the hurt of rejection that you have felt.

Now, it isn't your responsibility to take care of her.. but disengaging doesn't mean you have to do "nothing" for her..   It's all voluntary and at your option.. no need to bend over backwards really. 

But, also keep in mind that for all the 'nasty notes".. it really may not be as personal as you take it.. I know it seems that way.. but it may be more complicated than the surface.

My OSD would write things about how she hated her sister.. wished she would die.. be kidnapped etc.. I know a lot of it was because when the YSD came along... her parent's relationship was ending.  So, I think she saw her as somewhat the cause of all that.  Does she still want to kill her sister as an adult?  No.. they have a pretty close relationship... so.. sometimes the lashing out of a child is not as literal as it seems.

I think it might help if you connect the dots for them, instead of just saying no, maybe add you said or did ABC and XYZ, and I really don’t feel like doing LMNOP for you today.  I disengaged slooowly.  I have no problem re-engaging if I’m being treated with kindness and respect (or in the case of taking her out, treating others with kindness and respect), but that seems to be beyond my SD’s capabilities.

When I was younger I had a babysitter that I acted like a major brat for. When I was a little older I ended up somewhere where she was - I dont remember where or any details but I do clearly remember asking her something and her asking "are you going to be nice to me?"  I got the message pretty clearly. You could try that next time she asks for something like her hair to be curled. That's assuming you want to at all though. If you dont I wouldn't consider saying no mean.

Dont be mean...that is not right. 

also, it  does not  mean be a doormat.  HER dad should be making sure his child treats you with respect. It starts with him.

Your right, you dont not have to do anything for anyone when they treat you like garbage. Cooking dinner for the family, is not cooking it for her. Having a pedicure as a gift from you to her "girls afternoon' wouldnt happen if i was treated like garbage.

Instead of just "no" try "not this time" or the more direct  "I'm sorry but ever since you said you wished I was dead, I just don't feel comfortable taking you around with me".

At the end of the day this is still a child. Her brain is not fully developed and she doesn't realize that she has caused permanent damage because she can't truly comprehend permanent right now. Her brain won't let her. That does not mean you have to take it or that you have to accept her behavior. Finding the balance of disengagement that works for you will take time. Disengagement isn't meant to be cold, just.... not invested.

I do nice things for people who are nice to me. 

your feelings are understandable - that kind of rejection  and hostility hurt anyone’s feelings.  However, you might  consider taking a step back and truly reassess your options  before you proceed on this course, which will likely over time have unintended consequences.  Is there another way of disengaging that would allow you some relief but require less confrontation?  Only you know the answer to that.  Where is the girl’s father in this situation?  Why isn’t he addressing this and her obvious anger/hurt over her mother’s rejection? From your description- it appears that you and your SD have been left to unravel/deal with the consequences of a situation that neither of you created.  I hope that you can find a way forward that is positive in the long term.  Good luck.

Let her walk into a hold in the ground is mean.  She does not show you any respect, and Is only a person when she wants something from you. She has to understand that notbhow life works.  You have to show respect to get respect from others.  

If she continues to be vile to you except when she wants something, you have done exactly the right thing and should continue to disengage.  If she has seemed to mend her ways, and they stay mended for a considerable amount of time - ie I'm talking weeks not days, then you might want to reward her by doing one of the things she politely requests.   Like ntm said, "I do nice things for people who are nice to me".  

I think it hits girls especially hard when their BM isn't raising them.  SS may just be following his big sis' lead. Is BM in their life at all?

I can empathize with the feeling of wanting her to appreciate how much you are willing to do for her.  I've been there.  The harsh reality is, your SD may never appreciate what you do FOR her.  I'm sure you have the best intentions with positive and nurturing things you've done for her over the years, but she may not see it as positive as you might think.  It may just be a constant reminder of what her own BM isn't interested in doing.  I think of it like this: 

• If you have an excruciating toothache. Everyone is sitting around eating banana splits and someone says, "Awww...I'm sorry you're in so much pain and can't have what everyone else is having (a nurturing, loving, present BM).  Can I get you a sugar free yogurt instead (that's you! lol)?  It's really good for you!"  You may likely resent that darn yogurt and opt for nothing instead.  You may resent everyone around you for not realizing your pain.  You may very well want to throw that yogurt in their face and scream.  What you really need isn't something yummy and nutritious at all, but rather some pain medicine and/or a trip to the dentist!  

In that way, it's not personal toward you.  SD would most likely be that way with any woman in your SOs life.  As a wise person here on STalk told me...those emotional issues are way above our paygrade!  If I had it to do all over again, my SDs would've all been seeing a good therapist to work on their BM abandonment hurts before I ever moved in.  6 years later...I sadly have no positive relationship with any of them.  I now know though...it was never going to happen because they have hurts I, and not even their BD, can mend.  It's hard to let go of the dream of everyone loving each other and being appreciative just to have a big happy family.  But when you're in a family with kids who have been dealt the absent parent card... it's just not going to be a smooth ride.

Take care of yourself.  Love and nurture your biokids as you see fit.  Disengage where you can from trying to 'mother' your skids and try to just be a positive example of how human beings should treat each other no matter who they are.  It is never mean to let someone know they need to treat you with kindness and decency.  While you're at it...forgive yourself for wanting to say mean stuff back.  People get the best of us sometimes.  It happens. ;) 

A few thoughts.

My own mother didn't curl my hair.  I learned to do a lot of things on my own.  Bio parents are free to say No to their kids, so why shouldn't you be?  It teaches them that other people matter and they are not the center of the universe.  It's possible that you have been too accomodating in the past, and SD has gotten spoiled and taken you for granted.  Children don't learn empathy and gratitude from getting their way all the time.  The bratty behavior is not all because she's a COD, most of it is poor discipline.  If you were chasing her, that threw off the power dynamic in your relationship.

My kids are grown, so Dr Spock was a big authority when they were little.  I'll always remember this quote:

’’A child needs to feel that his mother and father, however agreeable, still have their own rights, know how to be firm, won't let him be unreasonable or rude.  The spoiled child is not a happy creature even in his own home.''

So remember, by depriving a child of WANTS, you are ultimately making them happier in the long run.  Your SD is not a baby, she's old enough to understand right from wrong, and she knows she's been a sh!t to you.  So far she's gotten away with it.  She needs to experience some consequences, or she's not going to learn how to treat people.  Don't make excuses for her.  You certainly wouldn't tolerate bio children treating you this way.

It sounds like you needed a break from her, and rightly so.  If you didn't get a break, your resentment would grow.  At least you backed off so you can cool off a little.  Maybe you'll feel better.

If she's naricissistic, like my SD15 is, she may be butthurt that you disengaged.  That's not the same as missing you.  It's more like a blow to her self importance.  And maybe being a little less Important will be good for her.

When I disengaged, initially the reason I gave for not doing things was "I don't want to" (now I don't give any explanation at all).  And that was reason enough.  Everyone else in our scenario was doing/not doing whatever the feck they wanted, so why shouldn't I?  You are even more entitled to do what you want, because you are an adult and these skids are not your responsibilty.  Maybe it's good for an entitled brat to be on the receiving side of not getting things because you "don't feel like it".

So if you want to do something, and don't expect anything in return, including gratitude, go ahead.  If you don't want to, don't.  Simple.  It's none of her business why you don't want to.

For some SMs, a break refreshes them and they are able to resume the relationship with stronger boundaries.  For me, I started disengaging slowly.  The less I dealt with SD, the more objective I became, and I realized that she was even more obnoxious than I realized.  Now I avoid her entirely.  I'm not purposely shunning her, I just don't have the stomach to be around her.  She's very toxic.  I came into the picture when she was 5 and disengaged when she was 12.  DH explained to her, that's what happens when you poop all over someone.  In real life, you treat someone like poo and they divorce you, fire you, evict you, unfriend you.  It's a hard lesson.  She thought she was entitled to poop on me forever.

By ten, children should have developed a strong sense of right and wrong.  Eleven to twelve is the age when children begin to understand abstract thoughts, perceive other people as distinct individuals with their own feelings and motives, show empathy, and have the ablility view things from the standpoint of others.  These skids are responsible for their behaviors.

Maybe this could be a catalyst for your SD to evaluate why she's been such a brat, and her behavior will improve.