I think that, if you usually find a relationship so stressful that you seek out anonymous sex to alleviate the pressure, polyamory is probably not for you. Polyamory centers on developing relationships, and if you can't handle the stress of one, then the stress of managing more than one would likely be very detrimental for you. You wouldn't find it easy to fully engage with each of your partners nor balance the demands of multiple relationships.
You may want to seek counseling or therapy to deal with this. You might still have some scars from your abusive relationship, or other factors, that are keeping you from having true intimacy in your life. The place to start is with yourself. Cultivate self-love, self-esteem, and a good relationship with your self, and you will begin to attract loving intimate relationships with others. A good therapist can help you along this path.