A "shetox" or a "hetox" are both essentially a cleansing of the opposite sex from one's life. They can be focused on one individual (cleansing one's ex-boyfriend or girlfriend from one's life) or they can be a result of a stressful period of time that involves too much dating/random sex.
A spin-off of the term "detox", in which one cleanses their body from built up toxins by only eating certain healthy foods and not ingesting any processed foods, alcohol or drugs (caffeine included) for a set amount of time (usually 30 days, or less for more intensive detoxes), a shetox/hetox involves going for 60 days or more without ANY interaction with the opposite sex, i.e. NO phone calls, no emails, NO text messages, NO dating, NO sex, NO CONTACT, NO MATTER WHAT.
The point of the shetox/hetox is to clear one's mind and rebalance one's emotions after a time of particularly intense mental and emotional stress and/or heartache. Put simply, a hetox/shetox allows one to focus on oneself and get back to a place of healthy heart and mind, and basically, to get over the ex.
The break-up was so ugly that the couple mutually decided to embark on a 60 day shetox/hetox from each other.