According to several sources on a quick google, a hemoglobin below 6.5 can lead to death.
How close were you to death? Well, a lot of factors are at play here - your other injuries, how big the bleed was, any other health conditions you might have. You weren't in good shape, for sure, and thankfully, you were in the right place to get the treatment you needed.
So what caused the visions, as I guess we'll call them for lack of a better word, or memories? Again, hard to say. Maybe the medications you were surely on, the head injury, the low hemoglobin, or a combo, or maybe something else. The mind is a really powerful thing and has ways of making us cope with stressful situations. You may never know for sure about all of it.
Happy to hear you are on the mend, and are doing better now, but don't discount the trauma of this, both physically and mentally. Just as your body needs help recovering, your mind might, too. Lots of people need therapy after traumatic events like serious accidents.
Wishing you all the best as you continue to recover.
Hello~My thoughts are you probably had these visions, etc due to the meds and the stress of the accident. It sounded like a horrible accident, your body has been very traumatized by it so it is going to take awhile to heal, especially the brain and thoughts. I would take it as easy as possible and let your mind and body recover.