What helped me with this..... not that I had it with family, but I did see it with some friends, was I put this statement in my head and I used it around them, "safer alternative to cigarettes". Say it loud and proud, it really does help cause it shuts (some) people like that down ...or at least seems to help.
Try saying something like, "I'm soooo happy (hubby's name) is proud of my choice to use a safer alternative to smoking, it helps so much having him on board". The goal (IMO) the more you brag on the family that accepts the less comfortable they'll be in dogging your choice.
Good luck I hope it helps..... if not .... no biggy, cause really you don't need anyone telling you whats best for you, you've already figured that out, good for you!