With Javascript, I could make a form where you enter the info into each box, the code will them format it accordingly so the output will be neat. Once you hit send, it will take the info and open your desktop email client which you could then hit send!
As for making it so only you have access, I could add Firebase to your website which will ask you for a password when opening the website page and only if the entered password corresponds to what you have set on the secure server will it let you view the page. If the password is incorrect, you will be redirected to a different page, perhaps the homepage.
This will only take me a few hours to implement.
Message me for more info :)