He is more afraid of losing his wife, than he is afraid of joining a cult
Last ditch effort on that. Their own words say that the "believing mate" should not depart from
the unbeliever.
Watchtower
11/1/88 p.22 par.8 "When Marital Peace Is Threatened" 8
Stress is laid on preserving a marriage even if only one mate is a believer. Paul wrote: "If any brother has an unbelieving wife, and yet she is agreeable to dwelling with him, let him not leave her; and a woman who has an unbelieving husband, and yet he is agreeable to dwelling with her, let her not leave her husband. . . . But if the unbelieving one proceeds to depart, let him depart; a brother or a sister is not in servitude under such circumstances, but God has called you to peace. For, wife, how do you know but that you will save your husband? Or, husband, how do you know but that you will save your wife?" (1 Corinthians 7:12-16) If the unbeliever chooses to depart, the Christian will let him go. But the believer, hoping that the unbeliever may be won over to Christianity, will not initiate the breakup. Timothy’s mother, Eunice, apparently stayed with her unbelieving husband but imparted spiritual instruction to her son.—2 Timothy 1:5; 3:14, 15.
She is not to leave him if he examines the things outside of the WT literature. Just say you found some things
interesting that you heard about witnesses. You heard that they made many false prophecies in the past about
Armageddon arriving in 1975, and also by the end of the 20th century. You just want him to examine everything.
If it's the truth, then you will be more sure if you examine outside evidence. If you are sure it's too late for that,
then start reading those Steve Hassan books. They will show you how to make every opportunity to talk with him
into a mini-intervention without seeming like you are overbearing.
Meanwhile, continue normal relations with your son. Don't let his religion change who you are. If you can't give
him a gift for holidays and birthdays, give him and the wife gifts from your vacations or in the Spring or whenever.
Show him you care on his anniversary. They are allowed to celebrate that.