The exact wording of the will is of great importance in a case like this. If, say, it ended with "the residue of my my estate I give in its entirety to Fred Bloggs" then (assuming that the will didn't say anything specific about who should receive the asbestos-related payment) I would have expected Fred to get the sum in question.
However if the will only said "I give my car to Hilda Smith, my house to Tom Price and everything in my bank account at the time of my death to Fred Bloggs" then there's no instruction in the will which covers the relevant payment. In which case a 'partial intestacy' is created, meaning that the payment (and anything else not covered under the terms of the will) is dealt with as if your father died without leaving a will. (That would explain why it passed to his estranged wife).
You need to examine the exact wording of the will carefully, to find out which part of it would have included the asbestos-related payment. If you can find such a term then it seems possible that the estate has been wrongly distributed. However if there's no such term it would seem that everything is (legally) in order, even if it's not what your father would have wanted.