At this point in the game, you can't just have a "do over" as you have children to think about. Take every effort possible to create a happy marriage, get into counseling for yourself and as a couple and make your biggest effort of your life into saving your family. If, after a reasonable amount of time (At LEAST six months if not a year) has passed and you still feel like you made a mistake, then maybe you need to move on. But don't do it now and don't do it without first trying everything possible to make it work. Many couple's that are unhappy but stay together find out that the next year they are very happy with each other again, so hang in there a bit and work at what you have.