I am sorry, but there is no longer a right to sue someone for alienation of affection, which is what you are describing this man doing.
However, if your wife does not want to have contact with this man and he will not leave her alone, she can ask for a restraining order to require him to leave her alone. If he is harassing you or your family, you can obtain a restraining order as well.
Respectfully, XXXXX XXXXX't any way for me to know what you do or do not know about the law in any situation unless you tell me in your post - and you didn't tell me the information you already had. Also, you need to know that I did not recommend "waiting to see what happens next". I reviewed all of the posts on this question, and I don't see that anyplace.
Given your description of your wife's mental difficulties, I think your question belongs in a different JustAnswer section. I am going to "Opt Out" and ask for the question to be recategorized.
I've never used this advice process before. I get the problem with you not knowing my knowledge but I incorrectly expected some basic knowledge from simple Google searching would be expected. I find the offending person's actions are threatening my wellbeing, but don't really know what I can do about it yet. Hopefully there is some way for me, a husband, to put a stop to this before it gets too damaging to ones family and finances.