business problem

I have an agency business , myself and a partner are directors.one of my employess is my ex brother in law (I divorced dec 08) and he has been with us for 3 years.my ex wife is in the process of claiming Ancillary Relief and I believe that information concerning my business is going back to her via my ex brother in law. any ideas on how to deal with this to avoid an unfair dismissal claim

You only have something to worry about if your trying to hide your income. Most of the information he would be able to give to your x would be in the public domain through your accounts at companies house anyway. Can understand your annoyance but is he really passing on info that he shouldn't be?
All that said do you have some sort of confidentiality clause in his contract or in company policies which he is breaching. If this is so then you could go down the disciplinary route, if not and he is in all other respects a good employee would a quiet word suffice. Either way you would need some proof and not just suspicions.

Janey