Marginal previa with slight sepration.?

I'm 13 weeks pregnant and went to the ER yesterday with heavy bleeding and was sure I had lost my baby. I was happy when they told me the baby was fine. But they told me I had marginal previa with a slight separation that was causing the bleeding.I've been put on bed rest. I'm still bleeding today. I would like to know has anyone had this before and what was the outcome? When will the bleeding stop? What kind of risk is there to the fetus? It's really scary and I would really like more info. Thanks.