In my line of work, we see patients that have ruptured membranes at your stage all the time. If you don't go into labor, you'll be in the hospital for awhile. They'll more than likely give you Betamethasone to help mature the baby's lungs while keeping you on bedrest.
If you do go into labor, they'll probably try to stop it with Mag., unless you are passed 6 cm's...then they'll let you labor. (at least that's what they do here!)
Good luck! Praying for a happy and healthy baby!