I studied Psychology and just got my University degree.
We won`t be able to understand this man`s psyche or disorders since he`s no longer able to talk about them.
I guess he is an "Egomaniac", who is afraid of women. He kidnapped himself a girl that would fully depend on him and that he`d shape after his own ideas and wishes. He raised himself a daughter and lover in one. Mostly important: a woman that is fully depended on him and unable to leave! (I guess his mother rejected/abused him in his early childhood)
I`d also guess he could have been a "borderline personality", a person who suffered deep rejection or abuse in the early childhood and therefore couldn`t mature psychologically. Traumatized people "split off" their "hurt part" and "shut it away" (this explains this extreme double-life between "nice, normal man" and "child-abusing kidnapper"). He is therefore divided into a "mature, socially-functioning" part and the "extreme and hurt" part. Borderline personalities only see black and white therefore he probably didn`t feel guilty and didn`t take over any responsibility for what he did to this girl.
I guess all that he saw was his own loneliness and the rejection that he had suffered so he "had to do justice" for what had been done to his psyche - kidnapping this girl and "having a woman that would love him for good" was his attempt to cure his pain.
His suicide proves that he couldn`t stand one more person leaving/rejecting him.