Hi,
If the hacker changed your email address, it is very hard to recover the account, and it may already be permanently unrecoverable. I’m sorry.
Especially if the hacker enabled 2FA, this means the account recovery form may no longer work. You can try the steps below to see if they help: https://support.microsoft.com/account-billing/how-to-recover-a-hacked-or-compromised-microsoft-account-24ca907d-bcdf-a44b-4656-47f0cd89c245
If none of the steps work, I’m sorry to say that since the username has already been changed to a different one, it means the account has been taken over by the hacker. There is no way to recover it, and it is now unfortunately lost.