Take it one little bitty step at a time. If you don't know what to do, do nothing. Rely heavily on your husband, especially in the discipline department. There's no quicker way to alienate kids than to become a disciplinarian too soon. You all need a chance to get to know each other without the onus of the being the Big Bad Disciplinarian.
Most people come into a stepfamily unfinished business and unresolved wounds.
Unfortunately, in many instances, the stepmom is a convenient target. In order to find the courage to remove the bulls eye from her chest, a stepmom often needs to seek out help and encouragement. In reality, for members of a family to understand each other and eventually evolve into a loving unit, it's often necessary to have expert and supportive advice, counsel, or therapy. With help, we can uncover and neutralize emotional bombs hidden in our psyches. One of the major surprises for many of the stepmoms I interviewed was the extent of their anger.