Finding all this very confusing and would really appreciate any wise words!
I'll be as brief as poss, without leaving anything out...
DH split up with his ex-DP six years ago. They have a now-12yo DD, who is on the autistic spectrum, but at the high-functioning end (mainsteam school; gets the bus in by herself in the morning). DH bought the house they lived in on his own; it's entirely in his name and he has paid all the mortgage and utility bills ever since (he moved out when they split so that they could stay on/keep things stable).
DH and I got together about a year later, and got married two years ago. We have a 2yo DS and I have an 8yo DS from a previous relationship. Both are NT, as far as we can tell.
About two years ago (after a year-long period of negotiation with the union; his work were insisting on changing his job title and reporting line) DH resigned from his job and now freelances. As a result his income has about halved. A year ago, therefore (ie five years after they split up) he said to his ex that he now needed to sell the house in order that we were able to buy somewhere. He offered his ex a third of the equity in the house (tiny terrace but it's in central london and he bought it well over a decade ago, so that would come to around £225k). She said she wanted half. To cut a VERY long story short(ish!) they've been to mediation, and he eventually said ok to half, as we just want to a) move on with our lives and b) stop paying out £3.5k a month in rent and mortgage and bills on two houses, which we absolutely cannot afford (having to draw on my savings every month). She's now said that she can't countenance moving DSD out of the house, and wants to stay in it until DSD is 19 - and then she'll accept half the equity. She claims that under the children act, a judge will a) allow her to stay on in the house and b) that once DSD turns 19, she herself will be entitled to apply to have the house as she has ASD (hence ex saying she needs half of it then, to continue to house DSD; if DH doesn't grant that she'll get DSD to apply to court for the whole thing).
I honestly think she's taking the piss, but am now so bemused by the whole situation that I don't know what to think. Is she right? Could we really be in a situation where DH never gets access to any of the house he's bought and paid for? The very last thing either he or I want to do is leave his ex and DSD without anything - hence the offer of equity - but she won't admit that the other two kids have any rights, because, in her words, "they don't have special needs". The whole thing is heartbreaking, and hugely stressful, not to mention utterly financially unsustainable for us.
I'm so sorry for such a screed. Can anyone advise at all? We feel we have no choice but to go to court, but I'm worried we'll pay for that, and then be left with nothing. I'd be eternally grateful for any advice anyone can give!