I remember when DH told me the same: that I couldn't do anything for the skids to like/accept me; the problem was I (or any woman in my place) exist here in this space. Oddly enough, it's a relief to hear that from your DH, right?! 
There are no realistic or cosmic rules that we should love our partners' kids. 
It's great that you were able to accept the discomfort of the tension (you aren't the source of the tension) without acting to fix it . . . 'cause it ain't yours to fix.  Bravo! 

Thank you morningmia and standingstrong! Yes, it is everything for dh to acknowledge that just existing was my main crime. DH was inclined to think there was something I could do to change SS's mind. If I could just figure it out and keep trying, it would one day click, or so he thought. It's a relief for dh to let that go and to just let me be.

Standingstrong, that's what I aspire to. It must have been good to hear from a man of the cloth tell you straight up that you needn't feel obligated to the SKs beyond politeness. This is what we talk about on this board too. But for that to happen, it was important that DH and I to get on the same page. It was a big problem that dh had unreasonable expectations of what I was supposed to do. Variously, he expected me to be the scapegoat, compensate for BM's shortcomings, come to the rescue, etc. But as far as I was concerned, dh didn't sufficiently consider my needs and feelings because I was accommodating and seemed okay. Things have been better in the last few months because I made it clear to dh that I wasn't going to accept him throwing me under the bus anymore. It was so hard for me to put my foot down, but I did let him know that I could very well leave because of how bad it was. DH was upset that I would make a veiled threat to leave, but it also got his attention. Hopefully it will become the norm for me to come and go as I please. In retrospect, it's actually crazy that I would sacrifice so much time and energy to please someone who was NEVER going to accept what I had to offer.

Thinkthrice wrote:

Flashbacks! "You need to be the bigger person/adult in the room"™ as his feral brats would tear up my house every weekend, throw rocks at me, lip off something fierce.

Hahaha. I'm laughing about how the quote is 'TM'ed. That is exactly the oft-repeated motto that kept me on the hook for everything. The angry teen can come after me, bully me, and my dh can allow it to happen and look the other way, but god forbid if I become upset. Now that's the REAL problem! All of a sudden, DH grows an ability to detect anger, and blames all of our problems on my anger issues. Thankfully, we're getting away from that. Glad it's only a flashback and no longer a reality for you!

Hi Trudie, Welcome back!

DH making more of an effort to see my point of view has been everything. I think it's the main reason that my anxiety has nearly evaporated. I still remember some of the things SS did and worry about things that might happen, but I don't have a strong reaction anymore. DH stepping up has had a few very important effects. 1. I feel safer and can relax. 2. Since he's acknowledging my point of view more, my mind isn't constantly swirling with stuff SS did or said that "proves" my reaction was justified. In the very recent past, for many reasons, DH was trying to diminish or deny SS's hostility towards me. But it's like if at work, you've been picking up someone else's slack, or someone has been bullying towards you. You want these behaviors addressed by those who have the power to do so. When they don't, you go home every day worried about more BS the next day. With DH telling me that he understands the reality and will ensure that the right people will be protected going forward, I don't have to be anxious stepping into the situation.

Things could change very quickly. But one thing I'm learning about myself at this juncture is that my resentment and anxiety has its roots in the external situation and other people's actions, not just as a result of my internal baggage.That's important for me because I tend to blame myself for problems, mine and others.