How in the world to I attract this type of people?

Remember the guy friend I used to have that I haven't talked to in four years who showed me a track mark? Well, even if you don't, I've just reminded you about him. Randomly he text me today. Is there something about me that screams 'I'd love to hear about all your drug problems!' or 'Please, please, please break my heart by continuing your bad behavior after I've given you so many freaking chances!'? I'm tired of people not understanding why I hate drugs and why I can't stand people who do them. I loved this friend of mine so much, and he just used that love I had for him to break my heart. It's strange that the pain is still there, and even after all these years it's still fresh. Now he has the nerve to tell me that he's "mostly sober". WTF! There's no such thing as being mostly sober. Sobriety in itself is the practice of not drinking, doing drugs, etc. I can't handle his bull anymore. He still smokes pot, which is ridiculous. He's adamant that pot isn't a gateway drug, when it got him into cocain, heroin, and severe drinking. And more than anything, I'm so mad that I let myself get upset at him still and that I still actually care about him. I have too much love to give to people who deserve it than to waste it on people like him who continually hurt me. So then the big question is, why do I continue to love those who are toxic for my heart?