HELP relationship in RED

I met my girlfriend about 4 years ago she has a 15 year old stepdaughter who i've cared for and took her to many places holidaying and buying her treats and sweets but i've soon realised i've been wasting my time and she has learnt nothing, recently she got a boyfriend which i eventually warmed to but everytime i try and put her right my mrs intervenes and palms me off which makes me feel even more discontent as to why she bothered getting me involved in the first place, at 15 years old she constantly leaves packets of crisp chocolate wrappers etc lying all over the living room floor, can't cook for herself tidy her room or even flush the toilet after weeing and everytime i tell her off the mrs has a go at me which makes me feel unwanted and unloved, but at the same time even the mrs is giving me stress i'm constantly being nagged as she expects me to tidy up, cook, look after her, her daughter, pay the rent which i do, take her out and pay, pay for takeaways and look after the dog cat and parrot as well as chaffeur her around everywhere in my car.

i'm very stressed and confused have no idea where to turn.

am i being unreasonable ? i've tried teaching the stepdaughter that we flush after weeing, we don't leave litter lying around and that we all must do chores, but she just plays xbox and does nothing expects everything on a plate.

another question i would like to ask is that we were all in a restaurant and there was this couple the lady wasn't attractive but the man was, so she said to me omg shes unnatractive and he's good looking but if i had said that a woman was good looking she would have literally taken my head off and gone on and on about it.

thanks sorry for the rant but feeling in a lonely unwanted place.

As far as the teenager goes... Sounds like a normal 15yr old to me. At least she's not pregnant or smoking pot. I hope the worst my daughter does at 15 is leave wrappers and not flush. Talk to your girlfriend about giving her a chore. Such as dishes twice a week and taking out the trash. Nagging is obviously not doing anything so if she doesn't listen, her mother needs to take away her cell phone or some other punishment. It doesn't look like u are able to discipline her, your girlfriend doesn't let you. Which is her right definetly, but she should understand that you have been taking care of the girl so you should have a little say in the discipline. All you can do is talk to your girlfriend. A serious talk when u both are calm. Change takes time but if your gf just refuses to make any changes to letting u discipline then there's not much you can do. You'll have to live with it and make a decision on if this relationship is really what u want.
And as far as your gf helping you with duties, u need to tell her what you would like her to start doing. Be specific. And if she refuses, once again, there's not much u can do. Live with it or break up. Can't force anyone.

Why are you still there if you're so fed up with being used and abused? This is on YOU. Figure out why you don't have the ballzzz or personal boundaries to just say goodbye to the two of them when you're discontent is this bad. Neither of them are changing into who you want them to be so that's your clue to exit stage left.