Seduced by the Alpha King

I never thought this was a moment I would have to witness, my fiance, the absolute love of my life, cheating on me with one of my best friends.
"That was incredible, as always," Haley said with a seductive tone "No man has ever made me come as you do,"
Derek responded with a low growl "You're making me want to make love to you again..."
My hands shook through my anger. It seemed as though they both knew I was standing outside the door, and just needed to brag about their sexual exploits I hadn't known about.
"So when are you going to tell Alyssa about us?" Haley asked.
"Soon," Derek replied "Once the wedding is official, Alyssa and I can begin the process of making a child, once my heir is born then Alyssa will have fulfilled her use to me," he paused "You and I can raise the child as our own, our own little family."
"The very idea of you having to make a child with Alyssa makes me so…" she paused. "Jealous."
As a human, I was told that the mate relationship among werewolves is considered divine and undeniable. Believing in this, I uprooted my human life to reside in the world of werewolves with my so-called fated mate. However, my expectations were shattered when I discovered that all of this was merely a deception, and that I was nothing more than a tool for childbirth.
One thing was clear to me - I wasn't going to let Derek and Haley get away with this deceit.