How were you diagnosed as having genital herpes?
do you have hsv1 or hsv2?
Has your husband been tested yet to know his own status?
the herpes handbook at www.westoverheights.com is a free and useful resource for basic reading for more info.
grace
unfortunately, there is no sure-fire way to prevent him from getting it, but there are measures you can take that will greatly reduce the chance of him getting it. if he uses a condom every time you're intimate, that will cut the risk roughly in half. if you get on a suppressive medication therapy (such as taking valtrex daily), that will further reduce the chances. and of course, you should never have sex when if you have sores or blisters. doing those three things will reduce the chance of transmission down pretty considerably - from a 100% chance that he would get it if you didn't do any of the above to about a 10% chance if you do.
hope this was helpful, and i hope your situation finds a good conclusion.