Where in the world did you get the idea that checking your bank and credit card statements was snooping? It is in your best interest to stay on top of those things. Keeping an eye on your credit card and bank accounts is not snooping. It is important that you watch your money! It's called being wise and knowing when to open an account in your name to protect some of your assets and to ensure you have money to live on and take care of your family, epecially if you start seeing a lot of money going out of the account and it's not being spent on the family and home.
Have you thought about setting up your own account and putting some money aside in it? What about credit cards? You need to seriously think about having your name removed from the joint cards and setting up your own credit card.
We have had posters in the past that didn't heed our warnings about keeping an eye on the financials and assets and they lost a good deal of money and were responsible for quite a bit of the credit debt and home equity loans taken out during the MLC trip because they didn't think their spouses would do such things and then it was too late. Don't for one minute think that he will care if you and your children have money for food, etc....because once he's deep in MLC (if he is), he may very well spend like it's going out of style just to impress his young lady friend and have fun at your expense. It's all about them and what they need to be happy.
When we caution people about snooping, it is about checking their phones, email accounts, Facebook accounts, etc.