The worst betrayal is discovering someone we trusted has in fact been exploiting us.
Then comes the rumination on the wrong we've suffered, followed, inexorably, by revenge fantasies. Our lives become diverted because the addictive power of payback renders it impossible to focus on anything else.
But dwelling on betrayal, in fact, produces no healing, only feeds the bitterness, in effect eliminating any chance of happiness.
So why do we do it?
The media has been quick to condemn Chris Huhne and Vicky Pryce for various aspects of their self-destructive acts of retaliation, but the more profound question is, why two such intelligent and successful people could get so completely sucked into the vengeance trap?
What they did is, in fact, incredibly common, and daily witnessed by psychologists and psychiatrists as a recurrent cause of distress. It just normally doesn't get so much attention, and so remains one of the darkest, hidden parts of the human psyche.
In the rush to judge and denounce Huhne and Pryce, it may be worth pausing to consider how prone we all are to revenge fantasies, and how self-destructive these can become in our lives.
Psychiatrists Professor Mardi Horowitz and Assistant Professor Susan Meffert from the University of California, San Francisco, have helpfully illuminated our grim desire for revenge in their chapter entitled 'Revenge Fantasies' in the Encyclopaedia of Stress (Elsevier, Second Edition).
They argue that seething with anger has an energizing function, which can be therapeutic when we're feeling beaten up by the world, or our adversary. Nursing targeted anger encourages us to feel strong, while fear creates a sense of weakness and vulnerability.
Self-righteous indignation is popular across the media in general, and indeed many programmes, like talk radio shows, as Horowitz and Meffert point out, even seek to stoke it. These psychiatrists advocate caution in this regard, because revenge fantasies are easy to plant, yet hard to uproot. It was probably not helpful that in the case of Pryce and Huhne, some of those they may have turned to for counsel at a time of distress, were scheming to appear sympathetic, yet encouraging of revenge, for their own murky motives.
Sometimes it seems as if whole professions are founded on exploiting our weakness for revenge.
There is something possibly hypocritical about the press condemnation of Pryce and Huhne's spiral of vengeance inflicted upon each other, when it was sometimes journalists who were covertly inspiring it, as emerged during the trial.
Horowitz and Meffert suggest that after a betrayal, bitterness and resentment leads to self-righteous indignation, which then becomes difficult to shake off, because it feels so much like energy or fuel for the soul. Burning anger makes us feel hard and solid, instead of puny, hollow or apathetic.
Breaking free of the revenge trap is possible; argue Hororwitz and Meffert, but psychological treatment, in their view, starts with the insight that we can be strong, without self-righteous rage. Next we need to analyse our predicament, rather than replaying an endless loop of the revenge tape in our heads, which in reality goes nowhere.
After experiencing a traumatic betrayal, Horowitz and Meffert suggest asking yourself whether the perpetrator is an enemy, or perhaps, an unreliable narcissist. Their suggestion appears prophetic, when considering the case currently hitting the headlines.
Horowitz and Meffert believe escape from the revenge trap is only possible by avoiding demonizing the target of moral indignation (but is this what the press are up to today?). They are not suggesting passive resignation to enduring wrongs. Turning the other cheek, they acknowledge, may only invite more slaps in the face.
Giving up self-righteousness, Horowitz and Meffert believe, is not the same thing as giving up moral indignation. Ethical outrage is a healthy response to seeing people break rules, when they could follow them. Moral indignation is a key motivating force in the world for good, but is easy to confuse with the desire for revenge. Someone who had been sexually assaulted may deploy moral indignation, campaigning to counteract the exposure of other children to abuse or neglect.
This kind of exasperation, in the view of Horowitz and Meffert, is effective and adaptive, whereas chronic bitterness with revenge fantasies, is ultimately unproductive.
We know from other psychological work in the area of revenge that the idea of "accepting and moving on" is easier for those who assent we don't live in a just world. Pryce and Huhne, by dint of their professions, were both involved in over-arching understandings of society. We may want to consider how our leaders and politicians inadvertently reveal their real attitude to humanity, from their private behaviour.
Those involved in politics and climbing the greasy pole are often enamoured with controlling others, while seeking to be free of control from above. One of the best ways, in our experience, to help those ensnared by the desire for retaliation, is to explain unless they forgive others (rather than seek revenge) their adversaries will continue to have power over them
Horowitz and Meffert conclude that the most powerful antidote to revenge fantasy is a new adage: When you feel bitter, do good. Put another way: when you feel bitter, seek the good. They contend this is a variant to popular maxims such as: perform random acts of kindness and senseless acts of beauty.
The psychiatrists' reasoning is that usually we want to be virtuous when we feel wonderful, as when we are in love. Their treatment of revenge rumination is to do good, particularly when we are more despondent.
They contend bringing goodness into the world when we feel humiliated, affronted, fuming, and unsatisfied, most effectively counteracts self-righteous rage and revenge impulses.
'When you feel bitter, do good' works because it counteracts two customary but malignant reactions to being insulted. One response is to cave in and feel feeble, punctured, and degraded; the other is the opposite, a result of role reversal, to adopt a tough menacing role, lashing out at others who are weaker.
So the next time you are betrayed and start ruminating and plotting revenge, remember the advice from two world specialists on the subject - when you feel bitter, do good.