Under all these Blocker Addons, this is almost what I was looking for and also the most precise and best working one out there.
There is just one thing that still annoys me. When you are on a website and (accidentally or not) click on a blacklisted link, it closes the whitelisted tab you are on with it instead of just not opening the link in the first place. Not opening blacklisted links should also be a thing in general to not trash the history with useless links.
The two text fields could also use a bit more height - there is a lot of free and unused space below the save button.