The wife is jealous of you and she sees a way of putting you in your place by making you her slave.
Reducing you to a fuck-toy means her husband will never see you as anything more than a little fuck pet. She encourages him to fuck you mercilessly, and tells him that you are her gift to him.

She spanks you and abuses you, but also binds you, legs wide open, and examines your cunt and asshole. One of her objectives is to have complete control of your cunt. So not only is there abuse, but also cruel sexual manipulation of your body. You are ball-gagged at all times except when you are needed for cock-sucking.