Are my sons chickenpox contagious if I never had it?

Yes. Adults who have never had chickenpox (varicella) can get the disease if they are not immune. I t can be severe in adults and cause pneumonia and other problems. Call your physician because potentially you can be vaccinated if you were recently exposed or you can be potentially given antiviral medication.
Yes. I agree with dr. Sedman-and can't emphasize enough that you should call your doctor for an antiviral and/or vaccine. The disease incubates for 7-21 days after exposure, so you will probably need the antiviral. I caught chickenpox from a patient, had several complications, and missed more than 5 weeks. (before the vaccine or anti-virals were available.). You can also catch it from shingles.