Either nut up and file for divorce, or stop cheating on your husband. Even if he's cheated on you that is a line you really, really, really do not want to cross.
As someone who has cheated on their spouse please believe me when I say it's about the most awful thing you can do to yourself. Because once you cross that line you will cross it again, and again, and again. And you will wonder for the rest of your life whether or not you're actually capable of carrying on a monogamous loving relationship with just one other person.
And each time you do it, it gets easier the next time.
Basically you're high on the fact that someone else is injecting energy into your life, and you've been feeling neglected. Take the high road, do what you have to, and file for divorce.
What I like here is you're making him out to be the bad guy for cheating, yet you openly admit that you're using and abusing him financially for your own gain. You're also fooling yourself if you think the kids don't notice the behavior of their parents, and that it is not affecting them in a negative manner. Pretty much your behavior is hurting your children as much as his, and it's great when you have three children you get to emotionally screw up because neither of you is capable of being a loving, caring adult without using the other person in some form or another.
"Well, then," the Cat went on, "you see a dog growls when it's angry, and wags its tail when it's pleased. Now I growl when I'm pleased, and wag my tail when I'm angry. Therefore I'm mad."