It seems like you may be confused? I'm not sure what the point is of coming to polyamory.com, (polyamory being multiple simultaneous relationships that are loving, usually sexual, and often committed) and saying that letting your husband sleep with someone else is a bad idea. We're all about letting ourselves and our partners develop emotional and physical relationships with other people, that's kind of the entire purpose of this board.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.