I just wanted to say welcome to the forum.
I was also raised Mormon/LDS, in fact I stayed with the church until way into adulthood. (So, small world.
It sounds like you got into polyamory with high hopes, and have been disappointed in some of your expectations. Sounds like you're maybe struggling with a little jealousy also?
What (if anything) would make it easier to handle your husband's relationship with his girlfriend? Can you tell what's at the root of the jealous feelings? Is it perhaps due to the fact that you had relatively bad luck with the poly relationships you tried? What other things might be fueling these issues you're having right now?
I hope Polyamory.com can be of some help to you.