I've heard Rabbi Yaron Reuben saying women who do not wear kisui rosh (putting the dispute of wigs as an exception), are like a woman who sinned before her husband. The Rabbi said that the kohen used to first warn about the consequences of drinking the 'Sotah Water' and if she does not acknowledge, the kohen would then pull off the kisui rosh of the woman.
Can I please have a source for this? And also, what is the severity of leaving the hair of a married jewish women without a covering?