You may be writing everything down. You may say you want to settle.
However the problem as I see it is that you only want to settle for what you think is right ... From where I am sitting that is for your stbx and children to live in a much reduced property with a mortgage, for her to have a diminishing income, to have to retrain (or rather train for the first time) while looking after three children - including a small one - and in a matter of some 5 years become self supporting.
I know the ballpark figures here are very big but when you talk about wanting to get a "grape" from the fruit bowl, you are forgetting about the metaphorical fruit basket - ie an income net of CM and travel costs - of some £4k a month that you have at your disposal. This income will only get bigger (as your responsibilities for CM and your personal debts are shed) while hers will reduce.
You have been told several times that her contribution will be counted as equal to yours. As PWC of the children, her needs for housing will come first. If there is more than enough to meet the needs then she should also share in the "fruits" of the marriage. This may or may not include a pension share. Although my view is that her immediate need is for cash now for property rather than pension in future, as Dukey said, a judge may very well award her both.
A judge is simply not going to be interested in who loved who, who betrayed who and who may or may not be behaving spitefully. They will look at the cold hard financial facts and will make a decision based on the provisions of section 25 of the 1973 Matrimonial Causes Act.
The fact that she did not work during the marriage - and has a young child - will be important. You talk about her working more to get more in tax credits but frankly as your earning are so high I am somewhat unimpressed that you seem to want the state (ie me and other taxpayers)to help fund the family that you and she created together. I am pretty sure a judge would take the same view.
I am not opposed to the idea that your stbx should try to make up for her lack of training in some way - for her own self esteem as much as anything else. I am just completing a Master''s Degree and have retrained in another profession post divorce. But I did not start from scratch as I have always worked (and been the breadwinner for much of the marriage) and even then am still never going to be well off no matter how hard I work. It is also very hard to study yourself when you have a home, children and even a part time job to juggle.
At FDR you will have been expected to make a reasonable counter offer. I am afraid that if you don''t negotiate properly - and perhaps make a few compromises - and you end up at FH, you may be in for a rude awakening. This will be as well as a massive legal bill and potentially permanent damage to your chances of rebuilding a relationship with your older children.
With a net income of 7k/month 3k spousal and child maintenance is getting off light in my opinion considering she has the children full time and has little earning potential.
I agree with Dukey that a judge may indeed award her more than 50% of your pension which I am guessing is the biggest asset in the pot given your income so if I were you I would consider her requests as being more than reasonable and possibly ask where to sign.
If I told my husband I would accept less than 43% of his net salary in child/spousal maintenance, only take 50% of his pension and that he would eventually get 40% of proceeds of house sale he would be celebrating. My solicitor and barrister would never allow me to make such a low offer as they believe I am entitled to significantly more.
How much either party will get will depend upon the matrimonial act and will be based on lots of different factors.
When solicitors and barrister start making statement like you can expect this percentages and that we wont settle for anything less than, it usually results in disappointment and extremely high solicitors bills.
I am at risk of sounding like a scratched record (as are you) but I will have one last go at getting you to move away from your "poor me" position and waking up to smell the coffee.
You have gone on about a counter offer but so far we have no idea what it is. Referring back to what she asked for when you first left is simply not helpful or relevant. Neither is bandying about figures. Bear in mind that many of us here would love to have £600 a month for food, clothes and toiletries ... for one person!
If you transfer that to your stbx with 4 to cater for (including 2 teenagers who eat like adults and grow out of their clothes almost daily), that would mean she needs £2400 a month before anything to cover household bills, mortgage etc .. and I am pretty sure you aren''t suggesting she gets that.
There is a perfectly viable solution that gives you a deposit, her (short term) and you (long term) a substantial income and home and a retirement income for you both. It is set out in my post on page 3 of this thread together with the rationale.That, or something very similar, is what you need to be thinking about.
I would strongly suggest that you stop complaining about being hard done by and instead concentrate on a fair (to you both and the children) and workable solution.
You have exhausted my patience I am afraid and I fear you will do just that with the judge if you persist.