NYS law..life insurance beneficiary problem...sister named years ago or widow who was never named

A life insurance policy is a contract and the "owner" of the policy has the right to name whomever they want as beneficiary. In your case your sister was the owner of the policy and named you as beneficiary. You are entitled to the claim, not her husband.

Life insurance proceeds are paid directly to the named beneficiary of the contract. If the primary beneficiary is no longer living, the proceeds are paid to the contingent beneficiary. In order to claim the benefits the insurer will require, at least, a death certificate and a claim form (thay they provide). There may be additional requirements that the insurer may ask for.

The widower is not entitled to any of the proceeds just for being the widower.

Although the situation appears to work in your favor, this illustrates the reason that people should take care to change their beneficiaries when their life situations change.