Just to be clear. If you have had chickenpox you will carry the 'dormant' virus forever. If you are unlucky the virus can cause shingles.
Shingles is not contagious, but the little blisters of the rash are loaded with the chicken pox virus. This CAN infect susceptible people with chicken pox, which is why my pregnant team leader chased me out of the office the only time I had shingles 20+ years ago. FWIW, I felt a bit below par for axfewxdays before the rash appeared but had no pain. Doc gave me Aciclovir as soluble tablets taken five times daily for a few days and I was soon OK. Got lucky I suppose.