I hope I didn't scare you too much. It is def dangerous but you could end up being fine and the placenta staying put and being fine its just never a guarantee which sucks. The nurses all freaked out when they heard I had a complete abruption with it not showing up on the U/S and with no cramping or leaking or anything they said they had never had that happen before and I was at a hospital that handles all the High Risk for the most part in Phoenix. I'm also one though that never really has any symptoms of PE/HELLP and once I get bad I get bad quick, which I kept telling the nurses and Drs. As soon I got put on the Mag (on a monday) I told them we would deliver wed cause it was just too dangerous for him to be inside of me at that point and even at 25 weeks he was better off outside of me. He started doing worse on Wednesday (HR dropped and he slowed down on movement, they blamed the Mag).
Just listen to your body and def take it easy, Im sure they have already put you on restrictions so just follow all the Drs orders and take it as easy as you can. It's a good thing they are warning you now though and are talking to you about what to look for.
Also I just read your part about your brother passing away. I'm so sorry to hear about the loss of your brother.