how do I stop this insanity

I'm a 43 year old male adoptee. And i was adopted by two people who where about as distant and showed no warmth toward me as could be. I only heard "we love you kids" when my mom was beating me with a wooden paddle she had my dad make, because she was tired of hurting her hand. I think she broke about three of them on my behind and lower back before I figured out I could out run her. As for my dad, he wasn't the type to waist time looking for the paddle that i probably had hidden from my mom. He just ball up his fist and let me tell you don't ever get him mad when he is practicing his golf swing. Because those drivers hurt when hit about the middle of your back. They never let on that i was adopted well we I have a sister who was also adopted and is three years younger than me, who could do no wrong. I used to snoop threw there closet when they were not around and there was this three book set that said Your adoptive family. And i would flip threw it and not once did it dawn on me why those books where there. Not once. But the day everything in my world crashed it hit me. I was 15 when we were leaving from a visit with relatives back east and my sister blurted out "are we adopted" guess one of the cousins spilled the beans. And i still remember the look the old woman got on her face. And thats when 2+2=4. It took me about a week to say something to my mom and it was swept under the carpet so fast your head would swim. Don't talk about that it upsets your father is what she said. And that was that, for her anyway. I on the other hand what if'd and why for'd the living heck out of myself. O i also am ADD. By the time I was 17 i was into drugs and had left home its been about 10 years sense i spoke to my mom and my father had passed away 8 or 9 years ago. I hate my sister and my mom for reasons only i understand. But the sad thing is and what is killing me inside is I trust nobody and i wont let anyone get close to me I've lost a wife of 11 years I'm a terrible father to are four kids. I don't beat them they live with her. I'm just never there for them. I feel there better off without me. I've been with more women than i could ever remember let alone count and only four real relationships which all ended. This last one was 4 years up until a few months ago. And I loved her more than anyone I had ever met. And i pushed her away she could never be close to me or know me but i didnt want her away from me but when she tried to pull close I pushed and its killing me inside and I'm close to exploding if something doesn't change and i don't know what i should do. my first thought is eat a bullet. but i made a promise to a total stranger that i wouldn't so here I'm someone please help. would finding my bparents and get some long overdo answers help. Because i don't know who I'am or where i come from and its like this black area of my life that I'm so out of touch with.