From your description of him it does not sound like he is a sociopath. It does sound like he is an abuser, a user, manipulator and liar. It sounds like you are more addicted to him than actually in love with him. What are you getting out of the relationship? Are your needs being met? Are you passing up other potentially good relationships because you are so entangled in this? If you aren't in therapy I would suggest finding a therapist to help you understand why you would value yourself so little to remain in this situation. Good luck!