The tape recording is irrelevant, really.
And there is VERY, VERY, VERY little chance that a claim of IIED (Intentional Infliction of Emotional Distress) is going to survive summary judgement (here, being a dismissal for lack of establishing the elements of the claim).
See this is how it works. In regular terms, someone files a complaint alleging that a tort (a civil wrong) has occured, and a demand for relief. The defendant then submits an answer either denying the claim, or putting forth an affirmative defense (yes I did it, but I should be excused because). Throughout this point (and afterwards), the defendant can make a motion to dismiss the case on various grounds. The relevant dismissal would be summary judgement - that, the plaintiff can not/has not established the elements of the crime.
For IIED, Plaintiff has to sufficiently show the court that:
1. Defendant desired to inflict severe emoitonal distress, knew that his/her aciton would almost certainly result in severe emotional distress, or acted in reckless disregard of a high risk that severe emotional distress would come about from such actions.
2. Plaintiff has indeed suffered severe emotional distress (and I mean severe)
3. That Defendants action
caused the plaintiffs severe emotional distress
It should be obvious that elements 2 and 3 are not provable despite tape recording. There is NO DUTY TO ACT in America's law even when you can help someone. That is, if you saw a baby crawling off a cliff, and all it would take was for you to get up, walk over, and pick it up, you wouldn't be legally bound to do so...you could laugh as it fell off and died. No duty, neither criminal nor civil. There are exceptiions however, and one exception is when the plaintiff and defendant share a special relationship. But have no fear, the law's definition of relationship is not simply some highschool love, but traditionally recognized ones - employer/employee, husband-wife, mother-daughter, etc. Girl - Crazy Ex-Boyfriend isn't one of them.
But back to the procedural explanation....
Now, if the plaintiff can sufficiently show evidence of each of the element, then the court will allow the claim to continue, and THEN the normal trial (as you see on TV) with jury, and witnesses and all that cr*p start. See, what most don't know is that there is the preliminary "sufficiency" test that has to be passed.
Now, this is all in simple terms and there are alot of conditions/exceptions/and strategic motions that can be done, but for our purposes are irrelevent.
The main problem is that, your friend will need a lawyer even for the preliminary "Stuff" and despite dismissal of the claim, it might cost some bucks.
Hope this helps.
(This isn't a lawyer's advice, merely a law students. That said I'm confident that it is correct.

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