I forgot the main email address form my old Firefox account

So, I recently discovered that many passwords that I've used before have leaked online, and I've been changing passwords and deleting old accounts for days now. I've used Firefox for many years back in the day, but I can't log in my old account because it seems my old email has been replaced by another one, and my email is now the secondary email for that account. So every time I try to log in, I just get a message "needs main email address", which I, unfortunately, don't remember. I tried all addresses I have, but none of them worked. I need help to either get access to my old account or at least delete it. Any help would be much appreciated. I can share the email address I'm speaking of upon request.