I can understand how you feel. I never see skids and sometimes just the thought of them can annoy me LOL. The same thing one of my kids could do that is mildly irritating would incite anger for me if it involves a skid. Which is why it is a good thing 3 are grown and the 15 year old SS never comes here. However lying and baby voice in a 9 year old (boy in particular) are not normal and could result in rage from any step-parent! As for no initiative - my SS15 is a lazy sack of $hit too which is a big part of why I cannot stand him.

So all good reasons for you to feel as you do. But I fear this situation is not sustainable for you. You cannot live like this and you don't get a break from these brats. Sounds like if you stay with your partner, you have at least another decade. I don't think this situation will change, unfortunately. Living elsewhere at least part time is a good thing to try - why does your partner not want to try that out? Unfortunately it may be you did not sign on for this and should move on with your life, preferably with someone without kids.

I'm like that too. I don't want to be nice to them at all. I'll do stuff for them, this is rare, to please DH, but not because I want to do it for them. I also never act happy around them. I act like I'm tired and annoyed and indifferent. I don't make eye contact with them and look somewhere else like I'm busy whenever they are talking.  I act like I didn't hear them talk and they will ask again and  I'll say "huh oh I didn't hear you." I'll pretend to forget to do things for them and just say "oh I forgot". Or if I refuse to do something for them I'll just say something like "I didn't know you needed that". If SD leaves her stuff around the house I'll throw it in her room. They dont get invited on fun family outings. If we have to do something with them I'll tell DH I just want to walk around the park. I save fun outings for DD. I've had a long history with them and their bad attitude rudeness cruelty toward me and DD  so now I'm totally disengaged and I use the medium chill method. It's freeing. 

Too bad this perpetuates the stereotype of the Evil Stepparent.

Seems like your partner must not be a very good parent to be allowing these behaviors. I'm sure he would love for you to stick around and continue to deal with his kids so he doesn't have to - but as you said, it's not healthy for you to keep living in a situation that gives you such negative feelings. This is how people develop chronic illnesses and sometimes just flat-out die, from being in miserable, stressful situations.

If living part-time in your rental home will give you peace, go do it. Stop letting his desire to be a lazy parent keep you in such misery.

Why are you stuck there? Are you choosing to be stuck? 

Scratched your car with a bike? WTF. How does that even happen "accidentally"? Is your bf going to fix it? 

The stress of living with people you do not like and constantly annoy you is going to start wearing on your heath. Constant stress manifests emotionally AND physically. 

It is my opinion that you should reevaluate why you feel "stuck". 

These kids are too young for you to live in misery until they're 18. I'd move out whether your partner wants you to or not, before you become someone you don't want to be.

I find my biggest frustration is that if I redirect my kid,  he listens and if on the rare occasion he doesn't he gets a consequence.  With SKs, they dont listen,  they back talk and they are painfully disrespectful.  Even when you do something nice for them 5 minutes later the way they act they might as well just come out and say go F yourself.  So, no I dont want to interact with them, it's not an enjoyable experience.  I often put my headphones in, so they know I am not paying attention and just want to be left alone.  If SO isnt going to be here when they are here, I make sure neither am I.

This is why I am behavior focused in how I deal with people.  It lets me focus on discrete incidents, confront and destroy the perpetrator of those incidents, and lets me move on. They learn quickly that it is extremely painful to perpetrate that crap with me or people I care about.

I do not retreat, I do not abandon my place in the blended or extended families and I do not abdicate my position and any authority or status that my position in the mix provides me.

This allows me to not let the deep seated drama invade my life at any level, and they learn to keep their behavior straight or suffer.

It also allows me to not let the daily irritating minutia to cause me to behave in a way that I do not like.  This also allows me to be aware and confront those behviors in myself.

Shit happens.  All kids are going to just be kids periodically with poor judgement that is not toxic or even a poor decision.  I returned from a business trip recently and scratched the crap out of the front fender of my car when I allowed one of my bags to rub on the side of the car. Something I had done countless times before with no issues.  On that trip a foot pad on one corner of my leather bag had broken off and a sharp pin was sticking out of bag where the foot had been and I ended up with  a 6inch long thin scratch on my fender. It irritates me every time I see it. I have used rubbing compound on it a few times and it is becomming less noticable.

My point is, shit happens.  It may be irritating, even infuriating, but it is not always toxic, manipultive or a conciouse decision. Some times it is just careless random shit.

Deep breaths. Don't let irritation turn you into someone you don't like being and do not respect.

So... stop that.

You're not handling this effectively and I would suggest you get into therapy to sort this out in your head and find the right tools to help you manage.