You have misunderstood Epictetus’ point. He calls on the disciple (assumed to be a free Roman citizen) to own and control his feelings, not blame them helplessly on the object(s) of his desire.
As to the point of being enslaved- St. Paul wrote that if we do what we are ashamed of then we are slaves to sin. Like the obese person who eats and regrets, he is enslaved to what overcomes his better judgment. “The good that I would do, I do not; the evil that I would not do, that yet I do! Who will save me from this body of death?” (Romans).
A sincere devotee of stoicism would be less prone to domestic abuse because of the practice of apatheia (detachment from passions) than most; and he would be less likely to engage in unsuitable liaisons for the same reason.