Your husband is experiencing new relationship energy, or NRE. It was very cruel of him to tell you he loves this new woman more than he loves his wife of 5 years! Infatuation can be so overwhelming tho. He probably forgets how over the moon he was about you in the early months or years of your relationship. It's very important in poly to take care of your primary, be romantic, set plenty of quality time together, even when youre in NRE with a new partner.
My ex and I opened our marriage 10 years ago and I also experienced jealousy to see them cuddle, or tell me they were going out to the video store and not come back for 1 1/2 hours, things like that.
Now, I am with a woman who has been poly all her life. She is in NRE with a new guy but she still makes sure to make me feel special, to let me know I am her primary, and how much I mean to her, give me lots of sex, etc.
Besides this board, I find this website really helpful. It's by a counselor who specializes in polyamorous relationships.