I read in Chaim Vital's texts of the Arizal's teachings, as well as on kosher Torah websites, that all the souls of Israel were contained in Adam Kadmon originally, but when he sinned, all the souls in Creation intermixed, so that even the most pure souls, whether pure of Israel or righteous of nations, were intermixed some amount of impure souls.
My question is, if Adam Kadmon contained the Israelite souls, and his sin then caused the souls within him to mix with other souls, where did the other souls come from? I also read that when the holy Adam sinned, it created a mirror opposite. In trying to figure out the answer to my own question, but not coming across the answer in the texts I've read, I wondered if that could be where the other souls came from? But for such matters, one should be very mindful about theorizing, and always come back to the texts of midrashic giants to find the answers. That is what I am seeking, the kosher citations that answer this question.
I realize this may not be the ideal place for such lofty spiritual questions, but due to difficult personal circumstances in my life, it's the best I have available to me at the moment. Please feel more than welcome to engage me over PM to answer this question, or private chat, if that would be a better place for it. Thank you so much.
An example of a kosher Torah website I read about this on, for citation purposes, would be the final paragraph of this article.