Sorry to say, but sounds to me like you two don't really communicate. He doesn't tell you about this account and large sum of money, which he doesn't really know what to do with. You don't actually talk to him and ask him questions about it, but come onto an anonymous forum to ask people who you don't know and are renowned for being snarky and nasty to ask what to do.
I suggest that first you sit down, talk to him about the money, how he got it and why he's never mentioned it before. Then jointly decide how best to handle the money to maximize the benefits to your family. If you have no pressing need for additional income (not wants, but needs), and don't know how best to save, invest or use the money, then go to NAPFA (
http://www.napfa.org/) and find a fee-only financial consultant who will charge you by the hour, without trying to sell you any products, who can take the information about your family and finances and come up with a financial plan for what to do with the money to maximize the benefit to your family.