Oh, he is a complete d**k h**d. He is selfish and is the physical embodiment of 'Wants to have his cake and eat it'. He needs to take a flying leap off the nearest cliff. 

The way he barged into her place like he still lives there :O the audacity 

He's absolute trash and doesn't deserve any rights. Sunwoo should've let him rot in jail for the murder case even if it wasn't him.

Like any other human being, he is a complex issue. So I am at Ep. 14 and so far I guess both cannot let go of each other. He seems to care deeply about JSW but at the same time has another child he has to take care of. His feelings changed completely from saying "I love you" to "as long as you are gone then my life will be perfect" to running to the ocean to save her.  As long as there is no physical distance I suppose both will always reach out to each other because of one connection that will always prevail: being a parent of JY. 

Also, they should have thought clearly about this: what do they prioritize? Am I willed to give up the person I have loved a lifetime over some power struggle/revenge?