@deux
You can block users that you feel are harassing you. It also prevents them from PMing you and you will no longer see what they post.
I would like to note that unless it's something drastic like death threats or racism, staff won't take action over PMs. If you feel that these PMs between you and Paulo approach that level, please reach out to a staff member.
Paulo uploaded these scans because they are from a company where the license has lapsed or they've dropped the title for whatever reason. Those are the only type of official scans that we allow on MD and that makes them fair game. You do not "own" these scans because all you did was upload them to the internet.
Lastly...saying that you did something because someone else did it first isn't the best defense. Our rules are located here: https://mangadex.org/rules
I suggest you read them.