After reading your SWH:
Honey, NOT going to a lawyer is gonna cost you a LOT of money. He will hide money, he will withhold important papers, he will threaten to take the children. You HAVE to go to a lawyer now so that you are ready. Do you understand what I'm saying here? Pay a little now, or A LOT over the years. If you are CHEAP now, it will bite you in the butt so bad...
Original:
No, you didn't overact. He's not being truthful with you. You might try marriage counseling, if you want to try to save your marriage. But if he's cheating, he's cheating and he doesn't care about you.
Have you been to a lawyer? You need to go. You need to know what your rights are. You need to get all your ducks in a row so that your children and you don't get screwed financially.