I am creating a Discord Bot in Discord.Net. So first, of course this bot is not a professional project, but I still want it to look as professional as possible. And a huge part is the storage and process of user data. Sure, I won't get data like Credit Card info, private adress or workplace. I just want a user account, where you can personalize the bot for your server. So all the data I may have are a username, a hashed password and an e-mail (I'm still drawing a concept. Not sure if I need a mail, or use Discord for Authentication). But nevertheless, I want to secure that data, like it's really valuable.
So my first idea was to safe the data into an SQLite-Database, which I already use for the Bot itself (Things like Money, or Userlists are stored there). But you cannot properly secure such a database, it's not SQL. Another idea was something like a single encrypted file, where all the data is stored. but that can get messy and eat storage really easily.
Also, even if I would store it into the SQLite-Database, I still could see everything. The password may be encrypted, but username and e-mail won't be. As I said, it may not be a big thing, but I also write this bot to learn things for future projects, and safe data storage is really important.
How can I save data like username+password or e-mail adress, while making sure that the data is unlikely to be exposed to anyone, including me? And also important, how can I process this data (I'm using C# for the bot), cause that's what data is for.