I'd be grateful for any help making sence of a way forward out of my situation. I'm a mother of two amazing little girls, 5 months and 2.5 yo. I am unmarried and have been with my partner coming up to 10 years now. I've come to the realisation that we need to separate, things haven't been right for several years and delaying things will make it harder on the girls. This way my youngest won't even remember us being a family.
We own our house 50/50, and he has another apartment he owns 100% of,
that he's currently selling (the plan was to put some of that equity down against our shared mortgage). This won't be completed until October/November. Our house is worth roughly £698k (we bought for £545k in 2019 and we have a mortgage of £355k remaining. He's a high earner and I earn a decent salary (46k) but I'm currently on maternity leave for the second time in 3 years, so my career is on the back burner. I really wanted to leave my job to start a small business but that now seems impossible.
I want to stay in our house with our girls, but I can't get my head around now I can achieve this. I've been a naive idiot not to insist on marriage. I never thought it was that important and assumed one day we would get married. He was never keen on discussing it and always questioned my reasons every time I bought it up, insinuating I was out to get his money or something. I now realise he had good reasons for never proposing. He has probably 15k in savings more than me, his pension and the other property, which will sell for £100k more than he bought it for. He'll need to pay me child support but only if I get more 100% custody I believe. Which I know he'll fight me on. What are my options and how should I proceed?