Of course you did.

Of course you tried to warn her. There wasn't any doubt - you did all in your might to make sure she was safe. Maybe you weren't as... efficient in achieving that goal as you would've liked, but nobody could accuse you of not trying. So no, it wasn't you. It wasn't your fault. None of it was. You don't even wanna think about it. Not again, not now, not ever. You don't want to allow your mind to be plagued by those thoughts.