No. You are not alone. It is unnatural to try and live with children that are not yours. 

Disengaging may help, it's really not your responsibility to care for them - they are there to see their parent, not you. You are probably overwhelming yourself with tasks that are not yours to bear. 

And it's your home. You have every right to be able to come home from work and relax and watch tv if you want to. Tell them to scram and go to their rooms. My parents did, both before and after they got divorced. You are a paying adult in the home, just because you are not a parent does not give you "less rights" as an adult in the home.

That paradoxical feeling is pretty normal. I went through those same feelings too, exactly as you describe. I couldn't live a lie so I got my own place and don't go around when skids are there.

like an intruder in MY OWN HOME.

Something has to give, and it has to either be your control or your sanity.

I get the control piece. I want to do the grocery shopping because I want to choose what I want, and I want to cook so I can eat what I want, and I want to do clothes shopping because I can find better deals, etc.

It CONSUMED me early on as a SP because I wanted to be the perfect SM, and I wanted DH and his family to be able to spend time with the kids without having to do the other not-fun stuff. That lasted about two years before I crashed and burned, and the boyd were only with us EOWE and 50/50 holidays and summer.

You have to decide what gives. You can take the kids to school, but your DH can make lunches and easy breakfasts the night before that his kids can grab and go. You can tell the kids to stop sprawling across furniture or to go play in their rooms. There can be instituted "quiet time" where they read or watch a movie quietly. 

Ultimately, though, if your DH cannot support 50/50 parenting without you there as the babysitter, cook, maid, and chauffeur, then he needs to not have them 50% of the time. You need time to decompress just as much as he does, and you need to devote time to your own kids. It's not fair for it to all fall on you when you're also working.

He needs to step up, and you need to let him step up. Not just because you need the mental break, but his kids need to learn that dads are parents, too, and it doesn't just fall on the woman of the house to do it all. Dad may need to hire a babysitter or send the kids to daycarw after school. He may need to hire a maid, or take the kids out shopping on a weeknight after a long day at work. That's what HE signed up for when he became a parent.

So, I implore you to be like Elsa and let it go. Help where it makes sense and doesn't cause you stress, and remember that kids don't rule over your home. I think if you take back control of your safe space - your home - and give up control of the things that were never yours to be in control of - breakfast, clothes shopping - that you'll find your mind quiets down considerably.

Me I am.new here. I have the same feelings like u. I dont feel.comfortable at home. I am the woman of this house but ... . The only place that feel safe is our bedroom. When I am there and close the door I feel light. Without any sign of these problems. But start from one month ago that because of isolation of Covid we have to work from home.and.also SKids have to study online. SD has a room in our floor while SS is in downstair which doesnt have internet. So he went to our room.for online lesson. First for me.was good. Remember me how much I was comfortable with my parents too. But after he continue to be there for other things. Watch the serie. Call friends and ... . As I said the only place that I feel good was our room. I told to DH and after big big fight and bad behaviour they dont go anymore. May b it seems I am a monster. But they are not easy person they always complain for.everything. everytime the ground of living room.is dirty or accidentally the kitchen is not in.order they always complain. I am sure if he continue to go to our room.after start to complain about putting my private thing in order and ... I am very sad. I LOVE my DH but some.days ago when we had fighted and I took my bag to move out(i had no place to go because of Covid even the hotel) when I was out of that house ... I feel I can breath again in peace. I KNOW children are in the first level for my DH but whenever he say this its like he put a gun on my heart ... He wants everything for them. And they are never thankful ... besides behave very rude to us... plus their BM which used to be in the middle. I ALWAYS afraid of future ... that my Dh gives evrything to them.and we stay homeless. I AM 33 and try to be very rich and save money to save us from this situation ... its very strange. Also me I was the only daughter of my father and deserve to have a better life even with a man with a history. Sometimes when.I be sad for their bad behaviour just I wish that they be in the same condition.as mine in the future. In love with someone with history. Then I feel guilty even for being devil. 

   You're not alone. I feel the same way, my husband decided to take his son full time without discussing it with me first. I'm used to coming home to a quiet place and relaxing after a long day at work. Now I come home to a child yelling at his friends through his online game and it literally drives me crazy. There are times where I don't like to home come so I just go to my parents house and waste time there. I just feel unhappy when I come home because I feel like that time alone was taken away from me. 

            My husband and I have been arguing a lot because he notice me not wanting to be home sometimes. I just don't know how to tell him I don't want his son living with us right now. His son will act out with his mother just so he can come over to our house and my husband always fall for it, it's so frustrating. I wish we can just be married but live in separate houses.