You have no contact in your bio but I've run into this with founders a lot and you need to recognize that what you're going through is a period of grief and mourning. I recommend you look up some books on how grief is processed in breakups or deaths and see if you find points of similarity.
Kubler-Ross' "On Death and Dying" is a classic place to start, it's where the "five stages of grief" model was first introduced. Her version of it is a lot more complex than the pop culture, linear understanding that most people have. She mostly talks about the interplay between the five stages and how we ping pong back and forth in interesting ways.
Also, FWIW, I've found ChatGPT a remarkably efficient tool to "read" books in an area you're totally unfamiliar with and want a quick download. You start by asking it to give you a broad overview of a book/set of books and then dive into the areas you find the most interesting until you arrive at an actionable framework.