Welcome to the STD forum. I'll try to help.
I am skeptical your husband has developed herpes of his hands and feet. Spread of HSV to a new part of the body (medical term, autoinoculation) is pretty much limited to the initial herpes outbreak; it almost never happens in people with longstanding infection. And certainly it doesn't occur on multiple body sites, i.e. both hands, feet, etc.
There is one possible exception to this, however -- a condition called eczema herpeticum. When someone has eczema -- which is an enitrely separate skin condition, usually caused by allergy -- HSV can take hold in the eczematous rash. I doubt this is happening in your husband's case, since he is taking Valtrex -- which would make such a complication very unlikely. However, eczema herpeticum can be quite serious. Your husband should immediately see a health care provider, preferably a dermatologist to figure out what is going on.
Even if eczema herpeticum is the problem, there should be no significant risk to the family. HSV-2 is not an easily transmitted infection. The only risk to any family member is you, and that is only through sex -- and that risk is low as long as he continues to take Valtrex and you consistently use condoms.
I strongly suggest you stop worrying about HSV transmission until your husband's new rash has been professionally evaluated. In the meantime, don't speculate about prevention etc until the diagnosis is secure. I stress it is very unlikely the rash on his hands and foot is herpes.
Let me know what is found after your husband has been professionally evaluated. I'll be happy to comment further at that time.
Regards-- HHH, MD
Thanks! One note, my husband had been irregular with Valtrex over the past few months, so he did not have full suppression protection. We will seek out a doctor for possible eczema herpeticum and indeed will let you know the outcome via this forum.