Self-Help book for self loathing and intrusive thoughts.

I am writing a book and I have two characters that deal with self hatred. I would like to read a book that could help me understand self hatred better and ways of combating it so I can have the characters grow throughout the series.

ALSO, I would like to in general be a happier person so I think this exercise could help me as well.

If it is of any use to you in your recommendations, both characters are teenagers. One comes from privilege and does not like her life's path. She has an impish voice in her head that always seeds doubt into every decision she tries to make. The second character has serious abandonment issues and was raised in a physically abusive and emotionally neglectful environment. He has abhorrent and violent intrusive thoughts (more like visual scenarios than an imp). He projects an image of happiness and silliness to try to get people to want to be around him and love him, all the while neglecting to learn who he really is.

I know this is a rather odd request, but everyone was so helpful in my last post that I just can't help myself. Thank you for your help!