Welcome to the forums. Sorry you're a little confused and guilty. Part of what you're dealing with is NRE (New Relationship Energy) with your new partner. The NRE makes you bond with your new partner and that can make you feel as if he and he alone is the one for you, and can make you blind to the needs of your primary. That's why you see a lot of advice to people in the grips of NRE to make a conscious choice to make sure they are at least giving their primary some of that energy.
Your situation is more complicated because of the hurt involved. Your primary lied and crossed boundaries. Is it possible that you need to slow down on the polyamory until these hurts are better healed? Have you and your primary worked on these issues and worked to improve the openness and honesty between you?