Share of profits upon sale of marital home

[Imrahil]

Long-separated; divorced last year; own my own home now; and we have joint ownership of the marital home. This is now being sold.

The divorce court judge instructed that the nett proceeds be split 95%/5% in my ex's favour. I expect to have to pay CGT upon the sale, as it was deemed a second home (even though I haven't lived there for ten years!). For CGT purposes, is my share of the profit deemed to be 50% of the overall profit due to the ownership having been "joint" - which is what the accountant I've engaged is saying? Or will it be 5% of the profit - which is what my actual gain will be?

I'm not keen to challenge a professional, but 50% does seem unfair in this situation. When I first worked through the gov.uk site, under "How much did you sell the property for?" it notes that: "If you owned the property with someone else, only enter your share of the sale value." Which still isn't totally clear - "share" for me could mean 50% as it was jointly owned with one other person, or it could mean 5% as that's what I actually get.

Can anyone confirm either way please? Many thanks for any advice.