Playing unhappy stepfamilies - help!

[TheEggshellsareCracking]

Brief outline - I have 2 DCs from my marriage, now live with new partner (2 years+) and we have a DC together. In the beginning, everything was great, but the longer we live together, the more difficult my partner is finding it, living with my eldest DC (aged 15), to the extent that he can't be in the same room as her. DC just thinks "Yeah, whatever, he's a prat" and is happy to hide away.
Is there a way through this, in anyone's experience, or do I just have to leave, taking the older 2 with me? (Last time I reached meltdown, we concluded that I'd continue to see DS every day at the 'family' home, because I do the bulk of the childcare, and my partner would have him in the evenings and we'd try to see each other at weekends on occasions when the older DCs were at their dad's/with friends.) I could just about afford to carry on paying my half of the mortgage if I rented somewhere very cheap locally. It seems pointless trying to sell because houses aren't moving quickly round here, but are still going up in value.
If you're wondering why I'd be the one to leave, it's because I have no equity in this house, because my marriage cleaned me out, so all the deposit was my partner's, and if we're going to share custody of our DS, I'd rather he stayed in his home, so as not to upset him further.
Sorry if you all think this is nuts, but I can't think straight at the prospect of losing another relationship. Everything else about it is great, but this thing with the eldest and my partner is starting to tear me to shreds.

Soundslike your dp needs to grow up
your poor dd

Teenage girls can be very difficult, of course, but this sounds terrible. My DH went through a very difficult period with my DD (after all living perfectly happily together for 5 years) but she became a teenager, we had a new baby - lots of change which she didn't deal well with and it became a very negative spiral.

Luckily, DH realised he had to do something about it (as he wasn't coping well and he was the ADULT) so got into some counselling which worked wonders. They are great friends again now.

It must be incredibly damaging for her to live like this, so what is he going to do about it?

Tanga, I'm just pleased to read that someone else has had similar problems and come through them. Because I had my children quite young, I'm surrounded by people on their first marriages, with no understanding of what we're going through.

The basic problem is a massive personality clash. The closest thing I can compare it to is when a teacher and a pupil don't see eye-to-eye, and it's nothing either person has done particularly, and certainly not something that an observer can really understand, they just don't like each other. I still don't really understand it myself, other than knowing that my DP has been really badly treated by my XH and he sees similar traits coming out in my DD (it's the lying and being sneaky, mostly )

DD knows that if push comes to shove, I'll take her out of the situation. Tonight I drove her past a rental property I'm viewing tomorrow, just so I know what my options are.

Yes, he knew I had children when we got together, but as I said, things were great in the beginning...

BTW - DS isn't yet 2.

I'm a stepmum and went through hell when my DSS lived with us (from 12 - 17 years old, not the nicest bit!). He was 5 when I met his dad and we got on very well till he hit puberty. I think he felt much safer being vile to me than his dad, who he'd already lost once when the marriage broke up.

I still feel very strongly that my DH was stuck in the middle and never backed me up when he should have done. I had no experience of kids, let alone teenagers, and wish I'd known then that counselling was available. I think DSS and I came close to punching each other a few times. Have you considered family therapy? Don't let her drive a wedge between you.

I'm sure (having DDs of 14 and 16) that a certain amount of her behaviour would be the same with her own dad but it must be hard for your DH to take.

FWIW my DSS is now 32 and we get on really well.