Ex partner trying to claim half my house

[Cee123]

I split from my ex partner a year ago. I have just received a letter from Head of Civil litigation giving me 10 days to pay my ex half the proceeds of the house or they are taking me to court. I need a solicitor who will actually fight my case but where do I start? How do I find a good one locally in the Derby, Mansfield, Nottingham area? Do I need a family solicitor or a civil law specialist?
Urgent help or advice much appreciated. I'll post a bit more info.

Good idea, will post in legal.thanks 😀
He lived for 7 yrs, but initially had another home with his ex partner. I was going through a divorce so the mortgage company just took his name off and I continued on an interest only mortgage as I bought him out with a shortfall and paid him £500 a month for 2 yrs. I was the main wage earner and earned twice what this new partner earned. He continued to pay the mortgage, all services etc on his house with his ex- partner and teenage child for 2 yrs til it sold, retaining a joint bank account with her, whilst also paying for a substantial renovation project so it could be fit enough to sell. I even went with him to choose eg tiles for it! Meantime we'd also set up a joint bank account. Bills were paid from this and no, none were in his sole name. He's claiming half the sale value proceeds, around £50 thousand. Yes, he was registered to vote at my address. I had a very large property with third acre, an old property needing lots of upkeep, but he didn't do anything towards this, I did it all, though he did cut the grass! He also owns a sixth of his deceased parent's house which his living parent lives in. Do I need a family solicitor? He is using a solicitor who is Head of Civil litigation.
During our relationship I also found out he had copied all my passwords etc from a memory pen and put them on his laptop, including my personal bank account- I let the bank know. He had been taking large amounts of money from the joint and putting it into his sole account.
He did though pay my divorce costs at the outset, but looking back I realise his intention was always financial gain. I discovered he had led a double life as a cross dresser with lots of sexual obsessions and had been meeting similar men throughout our relationship. The domestic support / police said it was financial abuse, which I'd never heard of before. I feel such a fool, it proves love is blind!

I've PMd you OP