CMS claim during divorce proceedings - need advice (UK)

Going through a divorce in the UK and need some guidance on a CMS situation that’s developed.

Background

  • Initially agreed 50/50 split on children and all assets
  • House already sold and divided last year
  • Ex-partner has been increasingly difficult throughout the process
  • During mediation, I suggested we mediate all assets to establish proper 50/50 split
  • Partner has a business worth ~£200k in equity/assets, plus additional business value

The Issue

After I mentioned the business assets in mediation, she immediately applied for CMS. This seems retaliatory as we already share all financial responsibilities and childcare 50/50.

  • First CMS assessment: £13k per annum
  • Revised down to: ~£6k per annum
  • With mortgage, car, legal fees , in the short term £600 month I genuinely don’t have
  • We currently have no financial separation agreement
  • No child arrangement court order (both in progress)

My Understanding vs Reality

I believe I shouldn’t be liable for CMS given our genuine 50/50 arrangement, but I’m told I need to prove the 50/50 care split. However, while the court proceedings are ongoing, I don’t have any official documentation to demonstrate this.

Questions

How can I prove 50/50 care arrangement to CMS without a court order?

Is there temporary relief available while court proceedings are in progress?

What documentation should I be gathering now to support my case?

Any advice from those who’ve been through similar situations would be much appreciated. The timing of this CMS application immediately after discussing her business assets feels very deliberate.

TLDR: Ex applied for CMS after I mentioned her business assets in mediation. We genuinely share 50/50 care and costs, but I can’t prove it officially while court order is pending. Need advice on how to handle this situation.