What keeps me going is that when I take away all the step/in-law drama, my DH were made for each other. It also helps that my SD11 is a really great kid, when it comes down to it, and she and my BD7 love each other so much. I have packed my shit so many times in the past almost 5 years of living together..some of those times have yielded amazing changes in how things are handled...it just sucks that it had to get to that point those times. Things have been calming down and it seems we are (including BM) finally settled into our new roles/lives. I stay now to reap the benefits of all the hard work we have put in and make a life with my soulmate.

You need you and DH time alone. Away from the stephell you are in.
My relationship works because he makes time for just me and also his boys. We try the happy braidy bunch approach (I had a successful step parent from both sets of parents just like this so I am trying my hardest to try that...might not work)
You need you time and you need couple time. So important, date nights etc.
Hope you are ok.

We had SS 24/7 45 weeks per year. What got us through was that our marriage is the absolute and only priority for both of us. As equity life partners that made me an equity parent for any kids in our home regardless of kid biology. Raiding SS was out primary responsibility but the marriage was and is our sole and top priority. It was for the 16+ years that we raised SS together and it has been for the nearly 4 years since SS-22 enlisted in the USAF and launched.

Though it took a while my bride came to enjoy our 7wks per year of Skid free time. We had 5wks each summer, 1wk in the winter, and 1wk spring that we could do what we wanted to do when we wanted to do it just the two of us that did not require consideration for the kid.

Put your marriage first. Both you and DH must to this. Everything else is second to the marriage no matter what "else" might be.

That is what worked for us.