It is kind of sad to say goodbye to fastmail, especially with a small investment ending up with a thousand dollar headache of changing email addresses.
But there is a good ending: finally doing the right thing and getting a personal domain. And doing that is much easier today than in 2001, and I also know that I don't want mylastname.com which is what I would have purchased then. So instead of
mylastname@fastmail.fm, I will get the preferable
shortasiwant@mychoiceofdomain.mychoiceoftld.
After getting a personal domain, you need to be able to get email. As far as I know there are (at least) three options:
1) Run your own mail server. This is another thousand dollar headache, no thanks for a user that only needs basic email services and expects no privacy in email communication. Using one of the free big providers as a backend is fine for me.
2) Use an email provider that allows personal domains. There are a few that will do this for free(currently at least Zoho and Yandex), and probably always will be. You might have to change providers from time to time to keep free(beyond domain purchase) service. This also requires a little bit of playing with your domain records.
3) Have email forwarded automatically to another email address. This is easy to do when purchasing a domain from Google Domains for example. Any free backend for another email address to forward to will be fine here, and there will always be plenty of those.
A .com, .net, .biz, .org, or .info domain costs $12/year with free private registration and email forwarding for 100 users to any email address. So with 3 friends the new cost will be $3/year with a (hopefully more chance this time) lifetime email address.