Half a year I found out my boyfriend made up his "brother"
he used to tell me he did in an accident, but after doing some detective
work, I found out he never existed. I confronted him and he was in shock.
He used to tell me lies before but he was aware of them but he says he believed himself 100% that he had a brother, I know when he lies and I am
unsure if he was aware of it or not because he hates to get caught lying and rather kills himself than tell the truth. In this case though I do believe that he believed his own lies.

Now he told me, many years ago he was in treatment because he would be lonely and bullied and he would sit at home and make up stories, weaving in people he used to know and making up characters for them and sometimes becoming his own characters in real life situations.
Does anyone know what this disorder might be?
He doesnt really want to talk to me but I personally believe these two
things seem to be connected.

He also used to be addicted to porn and sex.
He doesnt have any treatment for neither but says he has it under control
but I believe its a mental issue he cannot control.