The fact that he wanted to experience a life with a family doesn't make him any less of a psychopath for impersonating someone's small child for years 24/7.
Also, resisting at the beginning doesn't make him any less of a pedo: he still gave in and became romantically involved with a minor. A normal person wouldn't fall in love with a child.
And don't say he was forced into the relationship: he should have the strengh and maturity to refuse her advances, and instead he goes "welp, she kissed me, might as well marry her then!".
I agree he's not as bad as other similar protagonists and that this should be expected from this kind of story (in fact i still like the story), but that doesn't make his parents' reaction any less justified considering how extremely criminally psychopathic, manipulative, egotistical and deceitful his behaviour has been with them.