Tabby, anyone can sue anyone else for anything at all. They had just better have proof of their allegations, or else the person they sue can turn around and sue them for malicious prosecution.
Then how does someone in a state that has abolished there alienation of affection laws sue the OP?
Intentional infliction of emotional distress. (IIED) There is a statute of limitations, which vary state to state. IIED is difficult to prove, though. A few things help:
1. Plaintiff has to prove distress, by either producing psych records, medical records, etc., showing ongoing emotional issues directly attributable to the A.
2. Plaintiff has to prove that the failure of their M was directly attributable to the A.
3. Plaintiff has to prove that the defendant's conduct would be considered "outrageous" by most people in a civilized society. Prevailing judicial attitudes toward adultery is that it is not severe enough to be considered outrageous.
4. Plaintiff has to prove that the defendant conducted the A to
directly cause emotional distress to the plaintiff. For example, calling the BS and telling them that he/she just had sex with the plaintiff's wife.
The distress would have to be considered severe. For example, suicide attempts by the plaintiff wherein the plaintiff has left notes attributing the suicide to the A, and the attempt must be documented by medical professionals. It is not enough to be upset about the A.
Again, the intent of the defendant would have to be to directly cause distress to the plaintiff. Another example: Defendant pulls into plaintiff's driveway with plaintiff's wife and honks the horn to get the plaintiff's attention. When he knows he has plaintiff's attention, defendant begins 'making out' with plaintiff's wife.
It is very costly to pursue IIED and difficult to prove. Just being pissed and wanting to 'get back' at the OP will be an expensive process that may result in a counter-claim, and will more than likely be dismissed anyway.