He is definitely not ASPD, neither socio nor psychopath. Neither primary or secondary psychopathy. 

As for secondary psychopathy, sure the childhood trauma took a huge toll on him but it never really ended up as ASPD.

What we can see is that he was  unable to distinguish his emotions and empathy, which he felt a lot of . so is this like  a form of autism? alexithymia? 

I was thinking the same thing while watching the show. I feel like he likely has CPTSD, and then maybe Autism (ASD) and/or Borderline (BPD). I was disappointed they didn't have someone fight for him to be re-evaluated when he was clearly misdiagnosed with ASPD (although I LOVED his wife screaming at the doctor for misdiagnosing and writing him off), but I was impressed with the sensitivity we already got since Korean media doesn't have the best track record when it comes to discussing/depicting mental health issues