I can totally relate as this happened to me too. And we were married but I wasn't being treated like a wife.. An equal partner who has a say in what goes on in the house. No amount of talking would solve anything as my DH was too busy protecting his son and adult child from any inconvenience and meanwhile they were allowed to do what ever they wanted in MY home.

So I asked them to leave and started divorce proceedings. I even told my DH to marry SD21 as she is being treated more like a wife than I was. The only way to get change happening is to insist on your boundaries being honored which unfortunately is normally drastic! So be it!! Surely it's better than being treated like a maid who gives blow jobs! Have a higher standard for yourself as otherwise unless you insist on being treated with respect he will continue to put you last. Men don't respect what who they can easily boss around. Stand up for yourself and follow through should you need to.

I was lucky I guess as the house was mine and I'm more than happy to live without their toxic dysfunction! That coupled with the fact I'm a confident, attractive and popular 50 year old woman who has so much to offer and my DH knows this and is scared to lose me to some up and coming man who comes my way... Lol!! I let him think that but I am totally over wanting a relationship as to me.. All men are such hard work and have so much baggage in our age groups! I would more than likely sell up and travel for 5 years!!

Good luck and put yourself first as your DH isn't. How dare he not have any concern for you and your partnership and expect you to be the maid. Don't let him keep treating you like that because don't forget.. You are allowing him to treat you like it.

Nobody tells me who I can "approach" about a problem. You have the right to go bat shit crazy on all of them about their sh**** ways.

Why be passive and accepting of horrible behavior?

Well, I guess if you truly can't see a way out of the relationship, your way out is to disengage. Just stop doing what you're doing. Stop caring at all about her grades. If her sucks, close the door. Why do you care if she sleeps on clean sheets? She's 14, she can change her own sheets if she cares and if she doesn't and her doesn't, why do you? Retrieve all your dishes, wash them and pack them up. Replace with disposable. Stop cooking for them! She's 14, he's a damn adult, who gives a flying squirrel what they expect? Make your own food, do Your laundry, clean what you absolutely feel like cleaning and then just stop.

Tell him since you can't approach precious about any issues he needs to start paying 2/3 of everything. She's not your kid, you have apparently zero frigging rights, why are you subsidizing the mistreatment? I want to know why you see no way out since you sent married but regardless, a big part of the issue here seems to be that you feel you have to meet this guy's expectations of you while he is in no way required to do the same. Why are you allowing the double standard?

I understand what you are going through. When I met DH, he had the kids 50/50, but now we have the kids full-time. I had paid 1/2 of all the household stuff (rent, food, utilities) for kids who wasted water and food regularly. I implemented an allowance system to get them to stop whining when we went to the store and to get them to start doing chores, but, like you, that backfired. And DH though would sometimes listen to me was also very protective and defensive, which caused me to shut down and not want to talk to him anymore about the kids.

It drove my insane and it continues to this day, but less so. I think about leaving the situation a lot but I now have DS, and it's much harder to leave. These are some things that have changed over the years to help. DH is responsible for making sure chores get done, whether the kids do them or he does it for them. DH pays more than 1/2 but less than 2/3 of the household, which makes me feel better. I disengaged. After repeatedly dealing with a defensive DH when I discussed his SS with him, I just stopped saying anything. He knows that I parent well, so my disengagement was a huge blow to him. He started having a lot more problems dealing with SS and didn't know how to solve them or wanted my input, but I stopped providing it. SS became such a nuisance to him that it finally clicked and he became less defensive and started dealing with SS's issues. I, in turn, because he was no longer defensive, give him advice about SS. I still get extremely frustrated with living with the stepkids, but I can deal with it better now. There are more boundaries and DH finally wised up.

Since you are not married anyway you can just walk out of the relationship. Tell him that the relationship is not really working out the way you expected and that you need some space.

Even better yet, tell him that it is your fault you just can't accept his child and you would never want to get in between the two of them. (Total bullshit but you are telling him what he wants to hear = no arguments).

I don't see any way out

Really? You don't?

You don't have to put up with this, you just don't. You can stop doing anything for them or you can get your own place.

You pay your share of the bills, you get a say in how the household is run. If your BF does not agree, get yourself a different household. Or make them get one, whichever applies best to your situation.

I just couldn't, and wouldn't, live in a home that causes me that much anxiety. To me, that is not a home.

The others have pretty much covered it.
If you are this far along you have really one choice right now.
Do you want to stay in the relationship?

That answer will determine how you move forward and what advice you seek.