when trying to prove your own existence a few things must be qualified.
1) what counts as existence? does thinking prove existence? what if we are all a hive-mind in someones dream, does that still count as existence? what if we are all just a bunch of computer code playing in some 2 year olds "sims 9001" videagame, would you still exist?
2) how would you know if you are any of these things? would you be able to tell if you are a hive-mind? do robots think they think? https://www.youtube.com/watch?v=wnyi-5S16Xk this rat is being controlled and told which way to turn etc, but the scientists claim the rat thinks it decides where to go. (they make it feel good by releasing endorphins when it looks left or right depending on which way they want it to go)
3) does it even matter if we exist? clearly i am here and you are part of my reality (or me to yours depending how it all plays out) does it matter if we are all just a figment of someones overactive imagination?
4) why did you take the time to read all of that?
1) Yes. I firmly subscribe to 'I think therefore I am'. If you can't think, you can't even think of your existence, and are therefore off the chart. Since I think with my heads, I plan to have both of them flash-frozen when I die, and installed onto a clone of myself when the technology is perfected. Though this will only result in a few more years of lucid thought, I will have no doubt that I have continued my existence, such as it was, and will be. Well, I could be wrong, but I'll be sure to tell your descendants if it works. If I were just computer code and could think of myself in these terms, then I would exist. I am still not sure you exist though.
2) It takes a village to raise a child. Left alone from birth, a child would mature into little more than an animal. We are prodded, goaded, encouraged, and threatened all our lives to fulfil a need in society. The very notion of good and evil are based almost entirely on doing for others vs doing for oneself. So, for the most part, the only freedom of choice we can execute is to ignore expectations and do what we want (ie the only way to prove that you are exercising that freedom is to demonstrate selfishness). That is not to say that if you do good you are a sheep - we have all have struggled many times with possible courses of action, and done the right thing in the end, but to the outsider, you can't prove that you are doing anything other than allowing principles and morals, programmed by others as decisions in advance, to do the thinking for you.
3) No it doesn't really. Sorry I don't have time to finish reading your post so I will end here..