She got divorced because she could not allow and ignore what was going on and could not tell Mr. Choi due to how fucked up the situation was. I'm pretty sure she doesn't like Joowon because she knows his personality and is waiting for her son to snap out of it. So sad, sacrificing her happiness for her son's own good. (/TДT)/ ┗( T﹏T )┛ ╥﹏╥
May your soul find rest and peace