A) You need a probate lawyer.
B) contact the New York State Department of Insurance. (Which is now part of the Department of Financial Services)
C) Under normal circumstances, the proceeds of an insurance policy do not become part of the estate. There are however times when it is added in. (again, you need a probate lawyer)
Since the policy was left to your father, it is more likely the proceeds will be added to the estate. His not knowing about it, doesn't alter this fact.
Whoever is taking on the responsibilities as executor of your father's estate, will be best served by a probate lawyer.