Can you tell me is nicotine gum bad for you?

Not especially: At least in most people, and if used as directed. It is not really 'gum' in the usual sense - the stuff is thicker and more viscous than usual gum, so it's harder to chew, and TMJ (jaw) pain and headaches can happen, as well as the stuff pulling out loose fillings etc. I have had a few patients replace tobacco with gum, then not be able to quit the gum. I recommend skin patches in tapering doses.