A crappy past does not result in a crappy person. Deciding to be a crappy person results in being a crappy person.
yeah well, people react in different ways to abusive childhood conditioning. if your past is fucked up enough and you don't have any postive experience for contrasting choices then being sadistic may be the only mode of thought and behavior you have to work with. if i had no one in my childhood to counteract the nasty imprinted behaviors my sociopathic mother was installing i might be a sadist right now. and then there are those who are literally born without the ability to empathize. it's a birth defect.
You have a heightened sense of self-awareness. This isn't anything to worry about, and you aren't psychotic.