So rundown of known curses:
Witch 1: Sees every living thing as a monster.
Witch 2: Everyone else sees her as a monster
Witch 3: Hears malicious/negative thoughts (unknown if true)
Varying curses of equal strength were applied to each of the 13 witches.
MC appears a cursebreaker. Everyone but him is affected by these curses. Each of these curses appear to be driving the immortal witches mad.