As You Stood By

I think it is similar in tension and the uncomfortable feeling you get, rather than similarity in the plot. If you are looking for thriller, Somebody is a good fit for you.

Both dramas are very dark and heavy in their nature
Both dramas have extremely similar plot
Both dramas are mystery and thriller in genre

—2 close friends come together to murder abusive guy
— aside from focusing on abuse, focuses on the perversion and exploitation of men
— family member refuses to see their son as the problem and seeks revenge at any cost
— will take you on an emotional rollercoaster