I'll put it very simply. Feeling like you want to escape is perfectly rational in this situation. Over and over, she's failed to respect you, and what good is love without respect? Set yourself free. You can leave any time you want. Don't forget that. There's no reason to feel trapped by a relationship that keeps hurting you and trampling over your desires, first for monogamy, then for honesty, then for fairness.... enough is enough.
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.