My gf wants to get married and have a baby but I don't like kids. The crying sound makes me want to rip my ear hair out. Seems like too much work and I don't want to be strapped to ball and chain. Will she dump me?
You don't like kids is pretty harsh. Try to just see them as miniature people.
You should be honest about how you feel and make sure she understands that you aren't just joking. She might hope that you'll come around to her wants eventually and you need to make it clear that it's your final decision. If you really don't want children, you should also only rely upon YOUR own form of birth control-a vasectomy for yourself.
You seem to clearly have an aversion to having kids at this time. Staying with her while knowing that you're incompatible with kids could be considered relationship fraud. Be upfront about your thoughts and hope for the best. Don't lie and say something like "maybe in a few years dear" either as that's just stringing someone along. Good luck!