I think Bluehost uses cPanel, so you can migrate to any cPanel or Plesk host fairly easily.
I would just take a full site backup, move all your DNS to Cloudflare (so you don't forget specific DNS records) and then just migrate to a new host that way.
As far as going after them legally, there isn't much you can do that is worth the time. You could possibly demand to be prorated the remaining amount of money owed for your hosting plan, but that mostly comes down to their TOS, and if you've agreed since they've updated them.