Why is it a problem for you for your husband to be in love with someone else as well as you? Why do you feel you have to make him choose? Do you perceive that his love for her has been lessening his love for you, or is it instead that it's being forced into this choice that is making him draw away from you?
And, I'm sorry, but, for the record, you do realize that you're at "polyamory.com", which translates to "manyloves.com"?
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.