I made the mistake of marrying young because I was pregnant and thought it was the "right" thing to do. If your grandparents are in a position to help you and support you emotionally, accept their support please. Having a new baby is hard work and you need all the loving support you can get right now. Your boyfriend doesn't sound very supportive right now.
In terms of the actual delivery of the baby...it hurts, I'm not going to lie, but epidurals are a life saver and the nurses can be great emotional coaches.
You have a lot on your plate right now remember to breathe and take it one step at a time. Focus on what's best for you and the baby right now, everything else can wait.
You are in my thoughts!