"It's ok for her to use any and all of the things in our household (most my things). It's ok for her to eat all the food she wants and to request certain meals (I food shop and cook and cleanup) It's ok for her to choose where she will and will not sleep, where she will and will not go. I'm good enough to contribute to providing her a home and everything her little heart desires but she can't possibly extend an ounce of basic manners and can't be in the same room with me."

This sounds like you haven't really disengaged. Don't let her use your things (unless it's clearly impractical to segregate - like tv, couch, etc). Don't buy her anything special. Buy food that you and DH cook and eat. If she wants something special, DH can shop for those items. Don't clean up after her.

Boundaries need to be established. If she wants to sleep somewhere outside of her room, although petty, I would make it as difficult or uncomfortable as possible for her.

And you certainly shouldn't be providing her everything her little heart desires. Sounds like DH really needs to step up his game and help you out.

It's really more suble than that. It's very much her demeanor and attitude. And her total and intentional need to act like I don't exist.

I give her credit she is very good at her game. She is the most passive agressive person I think I have ever met. She is sly and sneaky and very very manipulative

My God do we live with the same teenager..SD16 used to do that walk into the room see me and walk out, now I beat her to the punch. If she is in a room I make my presence known by sitting damn near on top of her...she retreats to her bedroom...I got sick of sitting in my bedroom in an 1900 sq foot home that I own...and pay the mortage on faithfully every month.

I'm not sure what you have considered disengaging on your part, but the details of your post suggest you aren't fully disengaged. Its a good start though. The emotional will come later, it really does take time. I will go through this point by point.

"When she pulls her thing of starting into a room and then seeing me in there and then turning back around and leaving, how is it I'm not supposed to take that as personal? "

--Well, what I do is reframe it. Hey, you have this magical ability to make an SD disappear!! If it were me, I'd love that ability. Sometimes I do have that ability. I'm happy for SD to stay away from me. I can't tell you how many times I have pretended she didn't exist. Boy did my SD hate that. Poor me whining to daddy didn't work either. I truly could care less about her ignoring me. Just leave me the f*ck alone.

It's ok for her to use any and all of the things in our household (most my things).
-- Um, no. What things is she using of yours and where are you keeping it? SD doesn't even use my shampoo. I have everything of mine put away in the bathroom closet. no one uses my laptop or ipad but me. I don't like when people use my things.

" It's ok for her to eat all the food she wants and to request certain meals (I food shop and cook and cleanup)"

---Um no. Why are you buying food when the skids come? What I do is buy groceries on Monday for the week, then don't plan for the weekends. I don't cook or cleanup. SO does. UNLESS SO is going to do this with me, I don't cook or clean any skid messes on the weekends. Occasionally SO will get a hair up his butt for a home cooked meal. HE goes to the grocery store, sometimes I go along, mostly not. HE pays for it. I never spend money on skids. When he comes home I will help him cook and clean up IF I'm going to eat too.

It's ok for her to choose where she will and will not sleep, where she will and will not go.

---Well that;s her dad's choice. If he lets her come and go as she pleases, that's on him.

I'm good enough to contribute to providing her a home and everything her little heart desires but she can't possibly extend an ounce of basic manners and can't be in the same room with me.

--- No, you shouldn't be contributing to providing her a home with her little hearts desires. If dad wants to, that's up to him. You don't.

I am just fed up. I don't even know how to express my extreme irritation to DH, at least in a productive way. It's not like he doesn't know I'm really irritated, he just seems to not understand why.

-- You're irritated because you aren't disengaged. You are still doing for her and expecting something in return. The idea is to stop doing for those who don't appreciate or who won't do for themselves. Then there is no expectation and no frustration.

Hope this helped!