Hi,
i had the same with my Mum who passed away 2 1/2 years ago from cancer,
she seperated with her second husband 5 years prior to that, during which time he was trying to get a divorce from her, when he found out about her illness, and what he might get he decided not to go ahead with the divorce, and my mum made a will, since they had been seperated and not living together for at least 5 years the solicitors decided that he had no say in the matter and it was resolved.
only saying that he could contest it, but luckily he didnt.
hope this helps