I think your feelings and situation is the norm, so many things you shared sound so much like my story. I mean 2 teenaged SD, 18, 16 now and thankfully for the 18 yr old, that one has moved out. The 16 yr old has made it clear she prefers to live at a boarding school and despite my disagreement, DH has gone along with her wishes for the last 3 years mainly to have a somewhat normal life at home.
There used to be the closeness between us, as you spoke of, before they hit the teen years but also, BB has made it totally impossible for SK's to feel or express anything like love or friendship, especially considering I have done her job and then some for the last 6 years.
BB has shown her level of maturity with countless phone calls to me where she called me names, cussed and swore, then hung up. I felt it beneath me but there was the one time I called, called her a #### because she can't say none of it to my face and dared her to and of course she never did. In fact, the times she has come knocking, she had her sweetest smile and pathetic 'poor little me' body language when I answered.
BB is a master con at getting people to feel sorry for her, in fact, that is how she gets by in life, everybody feels so sorry for her, they take care of all her problems for her. She does not have to get a job, pay rent, nothing because she leeches off others.
REgarding SD, I'd look at it as my own kids hit a certain time where they decided they hated me (it was about 14 for them all) and then they reacted negatively to pretty much anything I said. So with my own kids, I raised them as a single mom and they still turned on me, of course they outgrew that phase and now, we are as close as ever.
I have seen SK's do same with DH, which has broken his heart but he pretends it doesn't, pretends to be made out of stone.
Here is the ironic thing, his ex - their mother ran off with another man, then proceeded to jump from one man to the next, pretty much bedhopping for the last 11 years and she is 'stunningly beautiful' as DH has said, so she can do that, despite her age.
So when SD, 13 ran away with a boy, DH acted with no feelings, no heart, and said simply, she's gone. I swear he acted as if that was his ex. I of course balled my eyes out, yet wondered where did these feelings come from? I am not her mom, yet it hurt as if I was.
Yet when they betray us, we are hurt and angry. Now, my SS, 15 is fairly decent with me, he was 4 when we first met, and his mom has been in and out of the picture haphazardly, more regularly when I am around, but it hurts when he whines to 'them' about me, his mother, his sisters, anyone of that side because I feel like I trated him like my son, but he is treating me like simply 'my dad's wife'. As their mother has brainwashed the 2 older ones to think.
All I can say is thicken your skin, do not put your heart and soul in them, because blood is thicker than water and they do not have the type of loyalty that comes with blood.