please use the "Blacklist Cleaner" of Aslain Mod Pack.
Go into game, click your Lists Tab, click on "Blacklist" and click together "ALT & Home" (between Insert and PageUp) at US Keyboard, or "ALT" & "POS1" (zwischen Einfg und BildUp) at EU/German Keyboard.
This should clean up your Blacklist. You also can set at your Mods/Config the Script for this Mod on a higher Number for entries, but, yes, it can lag your client if you have more as 5k "Special Friends" 😉
Its a german Screeny of my Client but its the last in that list what you need in every language you use.
Have fun at game