Wow! You have to ask yourself one question? Do I love this man enough to deal with this situation? If not, leave. A lot of people will say LEAVE HIM, but that's just not an easy thing to do if you really love him. You guys have 5 yrs together and your kids see him as "dad." I'm sure he knows he made a huge mistake and his head is probably just as messed up as yours is right now. You guys need to have an MATURE conversation about what you are going to do. Now is not the time to blame and point fingers. You have a real situation on your hands so arguing isn't going to make it any better. Stick to the important facts: "We're married, You cheated, There's a baby coming, We need to find a way to deal with this" NOT "If you wouldn't have cheated..."or "I can't believe you did this!" As hard as it sounds, try to be as civil as possible...good luck!