It won’t have changed by itself. Seriously, email addresses in a database don’t just randomly change. We had a situation recently where we asked someone to confirm their email address to us and they absolutely, definitely 100% said it wasn’t @live.com (or whatever) but when we finally sorted it out, they remembered they did have an @live.com address many, many years ago.
But let’s get this sorted out for you.
If you’re not able to change it yourself, start a thread in FCD and we can do it for you.