No, you don't need pills, and they aren't advisable at your age. What you're feeling is normal -- we're all scared to lose our parents. But you get over it. The advice to find someone to talk to about it was a great one, it will help you to talk it out. As for your Dad, if he isn't taking care of himself, he needs help, too, but sometimes people are who they are. You just need to be who you are, but if you're concerned about how he's handling this, he might benefit from hearing it from you and you might benefit by telling him how concerned you are.
Is there a school counselor you can talk to?