If the lawyer is ethical and has half a brain they will be trying to talk your ex out of going to court. It's an arsey and aggressively worded email because that's what they know their client would want to see. But - look past that- They've asked you for a proposal you're happy with the end the damn thing.
They want to bring him a negotiated outcome.
You respond something along the lines of:
"As discussed/as per my previous correspondence with 'Twat Ex's name' I do not agree that Valuation Firm X is independent due to their longstanding commercial relationship with Twat Ex.
I have obtained three genuinely independent valuations (attached) and am willing to agree to the houses value being the average of the three, and pay Twat Ex's equity out at a value of £X.
I will make this payment by bank transfer on 1 December 2023. Please advise if you would like this payment made to your firms trust account or directly to Twat X's account number: XYZ.
It is unfortunate that Twat X insists on prolonging the process of separating of our assets in this way. I believe any court application would be a waste of the courts time and an unnecessary further pressure on both of us.
I understand your client has the right to apply to court and will be representing myself if he decides to do this. Please direct all correspondence to me.
I have proposed a fair and reasonable pathway to achieve a fair and final outcome. I hope your client sees sense and agrees to settle this issue, so we can return our focus to our children and forging a healthy co parenting relationship for their benefit.
Yours sincerely,
"