Take the initiative. Say, "Mom and Dad, I've decided to take responsibility for my actions and my life. I am going to get a job and look into health insurance. I am looking right now to find a small apartment. I may need you to co-sign with me. I am planning on finishing high school and work at my new job. I have added being a father to my list of responsibilities. I am engaged and going to be married in 6 months. Mom could you please help (add name) with the wedding plans. Etc." Be sure to ask them about the cost of living in your area. You will want to stay close to them. After the birthing and the mom taking time out of school to nurse and take care of the infant, you will need a baby sitter. Moms are normally cheaper than your friends. Look into buying a car. Maybe your dad can help you with this. Someone is going to need a vehicle to get to and from the hospital, work, school, and pay the bills. Fess up and own up to your actions. Good Luck.
Be direct and tell them you are willing to take responsibility. Show them u know u made a mistake and they maybe upset or disappointed but show them u r gonna b responsible about this and they will learn to accept the new reality.