It is said that trauma and depression tends to drive an individual to self isolate and introspect to seek for answers. I swear it's like you just awakened and attained a modicum of Enlightentment, how profound you have tapped into inner intelligence/consciousness/awareness.
Here's my perspective (based on my personal experiences). Our 5 senses offers us the limited experiences of the 3D physical reality, the illusion of separation (i.e., separate from the animals, plants, the Universe and eachother), forgetfulness (before entering this physical reality we relinquish all knowing prior to incarnation).
"nothingness" by definition is: not anything, nothing at all, which means non existence, which is an impossibility, that which exists cannot cease to be, if it does, then it never was; however, if it does exist, then it always has and always will, it cannot NOT be what it is, which is 'Existence'. All the things that will never exist, already don't exist and will never exist, simply because they are 'non existence', therefore we exist forever. Out of the perceived limited dimensions of time (past and future) in the infinite Eternal Now, there's no beginning or end. Physical birth and death allows us to have the illusionary experience of beginning and end, this is just an elaborate illusion, there's no actual beginning and end, only eternity which is Now (Always Now). There's only consciousness in all of existence and that consciousness is in the eternal Now. Consciousness precedes all matter, our thoughts and everything else. Consciousness becoming Conscious of itself as Consciousness and with this comes everything else e.g. sub atomic particles, galaxies, dimensions and different levels/Densities of consciousness.
"i'm really that desperate to experience something else at this point that i'm getting excited about hypothetical other dimensions and existences lol." I have had (NDE) and retained some memories of other dimensional experience, they are what we humans call "Heaven", in fact any reality from the 5th Dimensions and above is what we would deem heaven (no experience of pain, at all). There's more dimension above the 5th where things are not physical. This current time space 4th dimension is what I deem to be extreme hell, the degree of forgetfulness and separation possible in this dimension is just extreme.
"what if we only "die" in this dimension/plane of existence but keep "living" in another? " This is exactly what happened. After my last death my consciousness was no longer in the physical body so there's no more experience of physicality (including physical pain), and I was so calm and serene (no longer plagued by heavy human emotions).
"just impossible to really comprehend not living, perceiving, and experiencing as a human, with the 5 senses" the physical 5 senses are just for the purpose of facilitating us with the short lived human experiences. These are lower physical senses, there's higher senses (e.g. 6th sense) for perceiving and experiencing higher dimensional realities beyond our lower 5 senses.
"i hope this is all just a simulation", it is, physicality is consciousness expressed as form and matter, nothing physical has an independent reality, everything physical only appears to exist cause we perceive it to exist. Matter/solid is not really solid, this can be observed under microscopes. This physical reality is just a virtual reality, a short scary dream we eventually wake up from.
"i "wake up" i can simulate whatever i want." You are unbelievably spot on. I experienced less limitations after death e.g no physical body = no heaviness, I could travel through galaxies and dimensions at the speed of thought.
"so probably not accurate. and i only desire it because it seems desirable to me" so in the other higher dimensions I was in, pain was an impossibility, so much so that for a being with the desire to understand (through experience) what pain is, will have to sent part of it's consciousness to the dimensions of pain, where such an understanding is not only possible but very likely, and we are in that dimension right now.
"who knows what other kinds of experiences/existences are out there?" Many, many, many, many of them and none of them as dense/painful as this one. "and i don't just mean in this universe/plane of existence if you will. " Exactly, Many, many, many, many realities out there.
"i'm insane" that's a valid perspective, however, I perceive you to be more sane than most human beings I have met through out my life. Just like my extreme level of pain forced me to ask deeply profound questions, you too are asking questions that truly truly matters, questions all mystics and spiritual masters who have walked the Earth have asked through out the ages.