Nothing. Once your brain dies, there is no more consciousness, no memory, no awareness. It will be like before you were born.
There has never been any scientific evidence of an afterlife. We live in a material universe, and as far as we know there are no others universes or dimensions, so where is the afterlife? If it is a place, it has to exist in this universe, and that just makes no sense at all. There has never been any evidence of reincarnation, or anything like that.
We have a consciousness because human beings evolved over millions of years to have a certain level of sentience and awareness. As a fetus develops, the brain grows to a point where it becomes somewhat sentient and self aware. This is why you have no memory of "before" you were born. A sufficiently developed brain becomes self aware, conscious, at some point in its development.
Why would you have any other body? That is absurd on the face of it. You can't ever have any other body. Nature doesn't make mistakes, it just is, and you have only one body.
There has never been any evidence that human beings have a soul. There is no soul-particle, no immaterial soul-substance or invisible spirit we have discovered, that floats away from the body at the moment of death. Where does this soul go, to another dimension? Is the afterlife somewhere in this universe we haven't discovered? That is just silly to think about.
I don't know if any of us can give you what you are asking for, because the scientific evidence doesn't exist and is pretty clear that when the brain dies, there is nothing after death. Your consciousness ceases to be. There is no pain, no suffering, there is no more anything. Life continues on without you.
you never took DMT? LSD? Psilocybin?
OP, look up psilocybin which has been used with terminal cancer patients.
Buddhism says that reincarnation is a misnomer, as we do not have a memory of our past lives (most of us) so even if the 'soul' reincarnates it doesn't mean much, as every life is a new storyline so to speak.
After death - the general stuff I read in the past talks about white light, being greeted, a life review...But the Tibetan Book of the Dead contains specific guidance on how to get a better reincarnation and get off the wheel of incarnation faster. My mum told me my late grandma saw a white light and family members who had passed on, greeting her as she was dying of cancer. She was in a hospice.
There are documented cases of children remembering past lives and literature out there. You want to possibly look up Dr Brian Weiss MD. He is quite comforting and his story is interesting. He was giving hypnotherapy to a patient when she 'regressed' into a past life memory that helped her feel better. He was a scientist and is one, and a doctor, and became convinced of the veracity of past lives and now teaches about them.
Scientists are beginning to agree that this whole world is a simulation - like a very sophisticated computer game. That is what neuroscience and Hinduism teach us, as well as quantum physics. That this world is an illusion created by our minds, through the experience of the senses. It's a matrix of experience. E.g. the documentary with David Eagleman on the brain shows how the brain creates our experience of reality rather than vice versa.
When climate change hits (sorry it's not cheerful!) then we will be the lucky ones as we have researched exit methods. Watching people die of thirst/starvation is less fun than exiting peacefullly.
OP, I honour your decision whatever you decide to do....I would recommend a psychedelic experience or two if your mind is truly made up, so you can explore consciousness a little. However, ymmv. I have never had one of those beautiful mystical experiences on mushrooms for example, I just found them scary - like they are the master and I am the slave. They are God in my opinion. The architects of the world. That is what they told me. I prefer weed by a long way. Ketamine is amazing. It saved my life this year. I am not addicted to it, but some peopel get addicted to it and it can cause bladder issues. With any drugs, check your contraindications.
Saying all of this - you asked for book recommendations, so my book recommendation is 'Dr Brian Weiss'. I forget the title. I will look up his website and add it shortly.
His book is called 'Many Lives, Many Masters'
https://en.wikipedia.org/wiki/Brian_Weiss
I was worried about the afterlife, then my depression became worse than any worries I had. Then Prozac helped me then Ketamine helped me - after years of torture with depression. But I am always in favour of assisted dying and pro choice. I know suffering. Not phsyical so far in this life as yet, but mental definitely.
Anyway, check out the website and Dr Brian Weiss. Sending you my best wishes. I also told friends and family for years I wanted to be dead - and it is a very rare few that can sit with you when you feel like that. We are here with you. You are not alone and you have done amazingly to suffer as long as you have and to get this far, no matter what you decide in future.
All best
