united-states
Most U.S. states recognize the torts of intentional infliction of emotional distress, sometimes called "outrageous conduct" instead, and the tort of intentional interference with contractual relations. An intentional course of conduct calculated to cause distress to someone implicates the first tort. An intentional course of conduct intended to make someone quit their job implicates the second tort.
Some states also recognize a cause of action for "prima facie tort" which allows for a lawsuit to recover damages for intentional conduct to harm another that does not neatly fit in the category of other recognized tort claims.
All but a few states (most notably among them, North Carolina and Mississippi) allow someone to sue for intentionally causing someone's marriage to fall apart. In North Carolina, Mississippi, and some of the other states where lawsuit of this kind are permitted, the damages can be very high. And, a judgment on this tort claim in one state is enforceable against the defendant found liable, in every other U.S. states, district, commonwealth, or territory, as a result of the U.S. Constitution's full faith and credit clause. In fiscal years 2000–2007, there were an average of 230 alienation of affections filings in North Carolina per year — a bit over 0.5% of the number of all divorces. The tort is also recognized in Hawaii, Illinois, Mississippi, New Mexico, South Dakota, and Utah, but it is frequently litigated only in North Carolina and in Mississippi. Many of the states where the tort is not commonly used impose restrictions on it that make it less attractive. In Illinois, Hawaii and New Mexico, these limitations make it exceedingly difficult to prevail in an alienation of affections case and recover substantial monetary damages. The standard of proof is lower in Utah and South Dakota, which continue to have actively litigated alienation of affections suits, although not used as often in these states as in North Carolina and Mississippi, for reasons that are presumably unrelated to the relevant legal standards that apply to these lawsuits.
A plaintiff prevailing on these causes of action is entitled to damages to compensate them for the economic harms they suffered, for the emotional distress that they suffered, and punitive damages (in addition to pre-judgment and post-judgment interest from the time the torts were committed at a statutory rate and the out of pocket costs of litigating the case apart from attorneys' fees).
If a judgment is awarded on these causes of action, it usually can't be discharged in bankruptcy.
This course of conduct might also be a crime in some states, although the question isn't detailed enough about the means contemplated to know.
Contemplating whether you can do something that is illegal and tortious to harm another person without being caught, that appears to be contemplated by the person making the post, just like contemplating whether you can get away with committing a crime without being caught, is beyond the scope of what is appropriate in questions and answer at Law.SE.
But keep in mind that these torts only need to be proved to have been more likely than not been committed in a civil lawsuit, and can be established entirely with circumstantial evidence. People who think that they are clever enough to get away with violating the law and harming others routinely find out that they were wrong.
