I wouldn't recommend living with an abscess for that many years, even if it is draining. I would suggest either getting an opinion from a root canal specialist (endodontist) or getting that tooth out and thinking about a replacement such as a bridge or dental implant.
The infection can enter the bloodstream or spread to your face or down your neck (depending on location of your teeth). As long as it continues to drain from the pimple though, it most likely won't spread as it'll just drain out and not push out to other places but I wouldn't like to have that in my mouth constantly.
Best to see a dentist and get it fixed asap.