Concentrate on top of the head Sahasrara and, about the moment of exit, it’s useful to precede it with relaxation e.g. tense and release muscles, breathe, empty the mind. Once “body is asleep and mind awake” I guess it may be tried to go out anytime. There would also be vibration’s phase (the Monroe technique gives a great elucidation on all of that), and I’ve read a method which suggests to direct them towards Sahasrara chakra.
I read about similar experiences. First thing I will do when I get out of my body is call Archangel Gabriel. First thing I would do is to learn from the master everything that there is to learn about Astral Travel before venturing anywhere.
Actually, the first thing you need to do, is to have an empty mind. You need to be ready for it before you start doing it. Don’t force yourself. When you master astral projection, you can leave from the bondage of the night, as Thoth once said.
I’m sorry that happened but I would say the opposite. Astral projection, from people I know, say it’s amazing. The only reason anything bad would happen is ill preparedness. If you just jump into it without research and learning techniques it’ll be a scary experience but the feeling of almost dying isn’t real, it’s just fear and fear is the one thing you need to give up before projecting