They do not need to be burdened by your heavy heart. Talk to them about your next time together. Set a firm date and make sure your husband has transportation worked out well ahead of time. Children need to know what to expect. They shouldn't have to wonder or worry when they will see you or dad again.
Kids usually love to use the computer.
Send them pictures of your husband or of you and the other kids if there are any. Send them the beginnings of a silly story you've made up and ask them to continue it in their next e-mail back. Make a easy to navigate web site for your stepchild to visit whenever he or she can. See if they can make it their home page. Instructions on how to do that are here .