To be fair, anyone prioritising someone else over the person who nearly lost their life sound awful.
No one is suggesting that what happened wasn't understandably stressful and traumatic for the OP. Of course it was. Putting it on the person who nearly lost their life is the wrong way to handle that trauma.
It's not low-standard of behaviour to be unable to prioritise someone else's feelings after a traumatic event that centred you. Imagine, just for a teeny tiny second, how traumatising almost dying is. Not only just in that moment but also having to deal with the cause of the near death experience. The tests, the medication, potential surgery, everything that may happen as a result of that.
Then, imagine that the person who very luckily was there and stepped in to help save your life, was whining on the internet that you hadn't considered how they were feeling during all this.
Which one is exhibiting low level behaviour here?
The OP isn't wrong to feel traumatised or stressed after an understandably traumatising and stressful event that none of us would like to endure. She is wrong to expect something from the person who is even more traumatised to help her cope with it.
This is where she needs to speak to friends/family and cope with it that way. Maybe the neighbour, in time, will come around and thank the OP. Maybe she won't, but that doesn't mean she's ungrateful for the help provided in her time of need. She could very well still be reeling from the shock of it all.