Are you and your wife in marriage counseling? If you're not, I really think you both could benefit from professional counseling. If cost is an issue, some therapists will work on a sliding scale or perhaps group therapy would be an option.

If counseling is covered under your benefits but your wife will not participate, please go without her.

Meanwhile, I'm confused about something in your question. You state that the 20 year old is "creeped out" by your wife's behavior but you also say you suspect there has been some "physical activity."

Does that mean you think your son's best friend is repulsed by your wife's behavior, yet he has given in and been physically intimate with her anyway?

If not, then your son's friend could change his cell phone number so that your wife will no longer have access or the ability to text him. He should also tell his manager that she is bothering him on the job; the manager is the one who has the authority to tell your wife that she is welcome to SHOP in the store, but bothering the employees during work hours is not permitted.