Ok, so my step daughter (there's nothing "Darling" about her!) has lived with me and her dad (and our DD) for the past 4 years. She is 16 and is at college. She moved in with us after her mum kicked her out, they'd been having problems for a few years - typical moody pre-teen stuff.
Things were ok at first, we moved to a bigger house so she could have her own room and we all got along perfectly well. Over the past 2 years she has turned into an ignorant, rude, lazy and just plain horrible girl. She recently announced that she has mental health problems (which she says started when she was about 5) and has gone through our GP for a referral to CAHMS, which I'm glad about as if she needs help then she's doing the right thing to get it, although she's blown off an appointment today because she couldn't be bothered going....(read into that what you will).
More recently, say the last month or so, she has been constantly answering back, talking down to me and her dad and throwing a strop if we ask her to do chores (she doesn't have many) she purposefully does the bare minimum or outright lies that she's done something when she clearly hasn't and her snide comments are starting to wear me down.
I'm also worried about the negative impact this is having on my DD, who at the moment is bright and confident and absolutely lovely with everyone (which I fear will change with constant exposure to her big sister who is a shut-in and refuses to talk to most people). She very rarely speaks to my DD and hates spending time with her, which really upsets DD as she looks up to her big sister and thinks the world of her.
Anyway, there's a tonne of history and our backstory would take up 3 pages... So what I am getting at is: WIBU to ask that she move back to her mum's? I've gone out of my way to make her welcome and to ensure she's loved and cared for (her dad and I have been together for 10 years), but it all gets thrown back in my face and the stress is now getting unbearable.
What should I do? (sorry for the long post)