Are my children at serious risk for developing chickenpox if their dad has shingles?

My husband recently developed what we believe to be shingles. He has not been diagnosed by a doctor but with lots of web research to try to identify a rash he recently broke out with I decided he appears to have shingles. Web research is also how i discovered the possibility of catching chickenpox from someone with shingles. I had chickenpox as a child at age 7 and survived but it was horrible. My husband and i have a 15 month old and a 28 month old who have not had chickenpox yet and i am concerned for them. Just how easy would it be for them to get it now due to my husband having shingles if he indeed has it? They have not had direct contact with his rash but are in close contact with him everyday. He shares food and drinks with them (not sure if that matters) and unfortunately I have caught him NOT washing his hands after he scratches the infected area. Besides the likelihood of them catching it, are children there age at higher risk for severity, and is there anything we can do now to prevent it after already being exposed?