I generally give out personal information on a need-to-know basis. Is there a reason your mother needs to know you have herpes? Would you like her to know about it? I agree with slacker that you need to figure out definitively if you even have herpes. Your first post was too vague to figure out if you even have it.
How do you know you have genital herpes? As far as telling your family, that's all up to you!!! I highly doubt you are going to put any of them at risk with it (unless your in some backwoods part of West Virginia). Now that your mom knows you MIGHT have it, I am sure there is a followup with her if you actually do have it. Do you lie or do you tell her the truth.. It's all up to you :)