Feeling Alone and Unwanted: Need Advice on Setting Boundaries

I hate feeling like don't belong anywhere I go. And people who tell me they care for me push me away. Ignore like I don't exist. When I speak to them they ignore me. I don't what I did wrong but I want to fix it. O want to make it better but I know nothing w I understand come of it. But I know they will come around when they need me for something...my body, my love, my affection, my time. I hate that I had this my whole life now. And I know the problem is me I need to set boundaries But I am at the point of my life that I want to hurt myself some way. So I think I am better off alone but I've been alone for so long. And I hate to admit it but I'm lonely...I never had real friend or someone that truly cared about without an agenda..