As a 35 year old financially-illiterate stay at home mom, I want to learn how to protect myself if something happens to my husband. Where do I start?

He is very open and shares all accounts and passwords with me. He has taken out life and disability insurance also. We have a net worth of around $500k with a portfolio of Roth IRAs, 401k, a house, stocks and investments in small businesses. I just don’t understand personal finance and if something happens to him (death, divorce) what I should do to ensure I am financially secure since I also have 3 kids below the age of 5. What resources/books/courses do you recommend? Or conversations I should have?