How do I find out who benefic was on spouses LIfe ins.

My husband passes away recently. He advised me of his insurance. However, his mother carried the policy and said he did not leave his kids nor myself anything after 33 years of marriage, he told us otherwise. How can I find out who was his beneficiary. Also, I feel as if my husband may have had another life that I was not aware of. How can I find out?