If one go by the generally accepted definitions and understanding of the sexual relations, specifically where spouses are involved, then extramarital sexual relations of either spouse falls under the "adultery" category. The adulterous sexual relations may be kept hidden from the spouse, may be known but without consent of the spouse or can be with the consent of the spouse, which I must say that in the Indian context is rare and such rare cases happen when both spouses are involved in it with mutual consent.
Adulterous sexual activity of spouse in the presence of the spouse without the spouse's active involvement falls under "Cuckold" category. If you have enjoyed watching right in your presence your wife being fucked by your own son and his other two friends, without your being part of the sexual activity, then you are a cuckold. Cuckolding need not be spouse's sexual act with only one sexual partner, it can be group sex with or without incest sex also. If you too join actively in the act, it will be a group sex, group sex may or may not involve incest.
Your story/ experiences till date are multi dimensional, not confined to one category. It has sex between spouses, it has voyeurism, mom-dad sex being watched by son/ daughter, incest between mom-son and father-daughter, adultery, group sex with incest and cuckolding.