just my 2cents (not knowing how much work you already put into it)
...in case of doubt always destroy the whole thing
next time do a proper ip-tables config and setup fail2ban to include monitoring website login attempts.
The "how to" to all of this is available via tutorials on DO.

p.s.: if you've already built a whole empire on that droplet I'd send an email to DO support - they are incredibly helpful

It's also probably not a bad idea to add a host based detection system (HIDS) like Tripwire or OSSEC. These collect details about your filesystem and configuration. It then stores this information to reference and validate the current state of the system. If changes are found between the known-good state and the current state, it could be a sign that your security has been compromised. This software can keep track of many different filesystem data points in order to detect whether unauthorized changes have occurred.
Good luck.

also, more simply, just change the login page for wordpress from wp-login.php to something else.

I do this now on every wordpress install I do, and it reduces those brute-force attacks to zero.

you can then delete wp-login.php, but I still add a line to my .htaccess to protect it, since it gets added back during updates:

    #prevents access to wp-config
    <Files wp-config.php>
    order allow,deny
    deny from all
    </Files>

#prevents access to wp-login
   <Files wp-login.php>
    order allow,deny
    deny from all
    </Files>