Having to deal with a Disney Dad!  Thankfully my DH doesn't do this any more.  I disengaged so I was quite lonely EOW when he would take the SDs on all sorts of outings and even once a foreign holiday, without me - admittedly my choice not to go. The rudeness from the SDs, particularly at the dinner table which was the only time I'd sit down with them.  The fact that DH did not get on their case over the rudeness, certainly not to the degree I would have wished. As you mentioned, dealing with a high conflict NPD BM.  Some of the other things you said, I couldn't relate to though, as I would never expect to love my SKIDs, I didn't even like them, and certainly did little for them, nor did I expect or want any credit.  

The total lack of control. 

I know that I am a control freak, type A person. I know that is both good and bad in my marriage. I take control and make sure that things happen. DH is great as my back up/support. 

When it comes to SS, my hands are tied. DH's hands are tied. I can't even be his support for so many things because it is always just waiting on the next court date so that something can be ordered and BM can ignore it and then we are back to court again. We can't just say- YES BM- THIS IS HOW IT WILL BE. 

Being 1300 miles away doesn't help us either. 

Crazy BMs and Family Court appearances. I've been in Family Court tons of times as a professional, and it was mortifying to be there repeatedly in my personal life, hanging out with the masses in their ripped sweatpants, tube tops and flip-flops, all because BM wants attention from DH and can't co-parent. 
 

Obviously, I didn't have to go, but I did it to support DH. 

Like the lovely Wednesday Martin says, "There are external forces, most beyond a stepmother's control, that may undermine her good intentions and best efforts with his children. These factors include loyalty binds, a child's jealousy and resentment, the Ex Factor, permissive parenting, cultural expectations about women and children, and a phenomenon called conflict by proxy."

I agree with all points! By my horrible step experience, I would also add: No matter how much time and effort DH and you put into giving your stepdaughter a healthy and nice childhood in your home, in the end, she will be an exact copy of BM. All your efforts result in living with a person with a terrible personality that you would avoid by all means if it were anyone else than your SD. (and you should avoid SD too; actually, it should be first on the list of taking care of your health, before eating healthy, exercising and taking your vitamins)

Also, all your good intentions, qualities, and values, will be used against you in a sick game to exploit you. 

Until you get rid of her as a grown-up, then you know that a purely evil creature is on the loose, making the world more ugly just by being in it. 

(ha,ha do I sound bitter.. I wonder why?)

For me, I resent being seen as an appendage to DH. Even by DH. When skids are around, I have no opinions, no preferences, no feelings, no interests. Oh, but I do have money. There's that.

Expectations....our expectations and the expectations of others and the reality of the situation are never the same. That is hard to deal with no matter how great your skid, dh or even bm is. 

I agree with the above and will add one that I've been struggling with lately. 

Having to accept people into your nuclear family who have vastly different values than you do. My Skids are lazy, entitled, rude...things I would never accept from my own children. Right now, they are doing absolutely no schoolwork. They are with us four days a month, so there is limited opportunity to influence them and when DH says anything to them, it becomes a big drama fest with BM. As an example, several years ago, he told both SSs that he expected them both to do all their homework every day, and BM turned it into a dramafest about how DH was always being critical and thought the kids were stupid. 

I have to turn the other way through all of this (the school one really kills me, I come from a family of educators and learning was never optional in my home) and pretend as if it doesn't matter, while also treating SSs like they are part of my family. As someone who has always valued integrity, this is hard. I feel like I'm also compromising myself big time. 

I realize this is also a DH problem. One SS - a teen - regularly has temper tantrums if he doesn't get his way and DH just tries to calm him down and will often give him what he wants, instead of telling him that this behavior is unacceptable. 

I spoke at length about this to my counselor this week and her only advice was that maybe it was good if I didn't spend much time with SSs. Easier said than done, because they come to my home twice a month! I'm just hoping that once everything opens up again, overly-dramatic SS will decide he doesn't want to come to our home anymore. 

It's like running an airbnb as was said above.  Except an airbnb with staff on hand and DH is the staff and on the whole they are nice to the staff but have to make sure the staff know that he isn't quite giving a 5 star experience. 

And the staff over the years is not even trying to offer 3 star anymore because even 3 stars is unappreciated.

At least DH sees and feels for himself why I quit the staff several years ago.