How can he sue you from another country? As in, what happens if you ignore it? Would you just be prevented from going to the UK or do they have jourisdiction in Norway as well? I never understood this part of his lawsuits.

There is something called the Lugano convention, signed by UK and Norway, making British judgments enforcable in Norway. In effect, it makes Norwegians subjects of British libel law when they use social media. No one is aware of this. Huge hole in the rights Norwegians have to freedom of speech