Before you make your decision on whether or not you want to get a divorce, con sider what is best for the children. When parents fight, kids get scared and it can effect them later.

I got divorced about sixteen years ago. My ex was verbally abusive and passive aggressive. She did some pretty nasty things in retaliation, and when I would go to visit him, she would tell the school to ban me from picking him up. If I wanted to take him a park with mountains, she said I was trying to take him across the border and kidnap him. The only reason i didn't put up a fight to keep him was at the time, we lived three states away, and If I made them stay in IN (which was my right), there would be any backup. At home, he would have two sets of grandparents wtihin 20minutes, so she couldn't hurt him as much with her tantrums.

The point is, we are adults that chose to get married. Sometimes it works, sometimes it doesn't, but there has to be trust and lying is not a good start.
Unfortunately, when you marry someone, you also marry your inlaws as well.
Adding kids with different biological parents is rough. If you decided the marriage is working, then get some counselling, for the adults and the children
Sam2