Hi, I'd like to help you with your question.
You can ask your husband directly if he has another family. There is nothing wrong with that. He may not be truthful, but if you are seeing evidence that he is cheating, then you have the right to confront him. He should not be involved with anyone else. It undermines the trust in your marriage. And if he is neglecting you and the kids (not paying the bills or staying home with you), then he is not doing what he should be doing as your partner.
Talk with him and tell him you find his behavior wrong. Let him know what you need (such as staying home, helping you pay bills) and be clear on what you expect. You do not have to be angry when you do this but try to use a neutral tone of voice. Until you know for sure what he is doing, then try to avoid accusing him.
You both can see a counselor as well. Talking to someone about the problems in your marriage can help you grow closer. But if he is not willing to go, go yourself. You need support to decide how you want to handle this problem.
To find a counselor, talk with your doctor for a referral. You can also search on line. Here is one site that may help:
Here are some other resources to help you as well:
Infidelity: A Survival Guide by Don-David Lusterman
My Husband's Affair Became the Best Thing That Ever Happened to Me by Anne Bercht
Ultimate Betrayal: Recognizing, Uncovering and Dealing with Infidelity by Danine Manette
You can find these on Amazon.com or if you have a library near you, they may have them for you.
Let me know if I can help in any other way,