Depressive Curse

The Breakup Curse (now amori damnum) is a curse to end a relationship. This is an unforgivable curse.

Although the curse cannot be reversed, there are preventative measures one can take. For instance, one may dodge the black bolt, block it with a physical barrier, any living thing not a human or goblin, a magical creature, or by the use of Priori Incantatem. The Breakup Curse, just like the Killing Curse is considered 'unblockable', thus shield charms won't defend against it. If it hits something non-human, then a black cloud similar to which when a horcrux is destroyed will emit (when destroyed via the Sword of Gryffindor or the Basalisk Fang). If it hits a horcrux, however, it immediately destroys it. It is the only curse that destroys horcruxes on contact of the black bolt."A loud voice behind me, was Lord Voldemort, yells the incantation: "Engurgio!""

- Voldemort, attempts to curse Christopher Lewis

Survivability
"People could in fact, survive this deadly curse. Although, the rate of which is severely slim, one could survive if prepared and responsible enough."

- Kingsley Shacklebolt's view of the Breakup Curse in the Daily Prophet

Chances of survival of the breakup curse is very slim. Unlike the Killing Curse, the Breakup Curse (is still fatal) is a slow and very depressing way to die if the effects are not treated at all or correctly.

Treatment and Health-Related Cases
There has been cases where witches and wizards have been cursed multiple times at once, putting them in a medically-induced breakup, and requires medical treatment, which are only available in wizarding hospitals like Saint Mungo's Hospital of Magical Maladies and Injuries.

Treatment Services for Muggles
Since St. Mungo's Hospital is not accepting Muggles (technically is no longer since the early 1690s), therefore, the curse is permanent and may inflict lifetime consequences, which is why the curse is unforgivable. But it can be treated through a series of blood tests and counseling and trained professionals, or admit to mental health based-hospitals like Spring Harbor

Notable Exceptions for Muggles
But Muggles can be accepted if any of the members from the Department of Health and Human Services gets consent with the Ministry of Magic. Unconsentual admission is prohibited and is a violation of the International Statue of Wizarding Secrecy.

Withdrawals from the Curse
This curse does have side effects if not treated immediately. For instance, victims like Christopher Lewis had to suffer lifelong damages from the curse he got during his second year. The symptoms are very severe, and is likely to cause death. Each phase depends on the time you were under the cruse effects. The longer you wait for treatment, the more severe it will be.

Withdrawal Symptoms
These symptoms appear a week to one month after treatment, and usually wears off after six months to a year of that.

Etymology
The incantation, amouri damnum, is Latin for Love Loss, but damnum, closely related to damnare, which means damn. Either way, it either means love to be loss or love to be damned.

Appearances

 * Fifteen Reasons Why and the Triwizard Tournament (First appearance) 
 * Fifteen Reasons Why and the Order of the Phoenix
 * Fifteen Reasons Why and the Case of Christ (Appears in flashbacks) 
 * Fifteen Reasons Why and the Lost Love
 * Fifteen Reasons Why and the Crimes of Crouch