for me, it was a lot of self-reflection and getting the opinions of other people. i‘m not an expert at all and don’t really think my methods are that healthy, but i tend to dwell on the past a lot. while it’s exhausting, it helped me realize i was a toxic friend to lots of people and i see myself being more accountable :) hope that helps

The most effective treatment for me is DBT. It doesn't change my traits (and I think nothing can change them), but it helps me regulate my emotions and be more tolerant. It helps me deal better with my bad traits.