Thank you for your supportive words. I think they are already coming out HotDAMNlifeisgoos 
I'll start writing but there's so much...
Background first. I'm a twin. Mum had us when she was very young. I have a younger sister who is 6 years younger than me and a brother who is 10 years young.
There was no cuddles, tenderness or affection. We were always compared to girls from school, compared (unfavourably) to our younger sister, pitted against each other and treated as a nuisance. I remember that I got the worse of it compared to my twin though, I think because she was quite an extrovert and would stand up for herself. When I was about 7/8 my parents would wind me up so much that I would be hysterical, in tears then call me into another room. I would walk in and they would take photograph of me. They even kept the photographs and would laugh whenever they took them out to show me or other people. They never did this to any of my siblings.
When I was 7, my mum decided to perm my hair. She rubbed the solution on and I remember it burning my scalp. I cried and begged her to wash it off, only to be told "if it hurts, then it's working". She permed my hair until the age of 9 and I think it's caused some problems I still have with my hair now.
She was always telling me I was fat. I did all kinds of sports and I developed early so I had a womanly figure from quite young. I was put on a diet at 10 years old where I wasn't to eat lunch and she would make me feel bad about eating. I recently showed my DH some of the photos where I was told how fat I was and he was shocked and sickened I was told that. Thing is, looking at the photos, I was nowhere near fat and a lot of it was that I was just taller than most of the girls in my class. I've always been told I was too fat, I need to be thin to find a husband, I should be like her.
For years, starting from early teens, she would tell me and my twin that it was our fault she had to get married to my Dad, that she wanted an abortion but was made to keep us. Basically, how much we've ruined her life.
She would confide me in about problems, including sexual, in her relationships, with my Dad and various boyfriends after they divorced. She would tell me about men who came onto her who were my Dad's friends. Dad didn't know anything about this and still doesn't. She put things in my head that shouldn't have been there and made me keep secrets I shouldn't have had to keep.
I was fairly bright at school and really enjoyed it. I wanted to go to university but she made it clear I couldn't. I should just get a job and start bringing money into the house. My uncle persuaded her to let me do A-Levels but she put so much pressure on me that I didn't finish the course. She felt I was too above myself by wanting to study and that I must think I'm better than her.
My younger sister has always been the blue eyed girl and my brother can do no wrong. My sister's boyfriend assulted me when I was 21, bruises, cuts the lot. My sister and I were both still living at home and when my sister bought in into the house a few days after, I said I didn't want him in the house but in front of him, she said she wasn't going to ask him to leave because he was my sister's boyfriend.
She even engineered a situation with a boyfriend to get him on his own and tell him I was cheating on him (I wasn't and she knew it) just so she could throw herself at him. I found them in bed together. She attacked me and told me to leave the house as he wasn't going anywhere. She then contacted my best friend to say I had got the wrong end of the stick, she didn't sleep with him and could they speak to me. She told everyone I was mad and seeing things.
I've had a lot of gynae problems and a few operations so I was thrilled when I fell pregnant with DS. When I got to 14 weeks pg, she told me that she was surprised as she didn't think I would get past 13 weeks. She put so much pressure on me, made me worry all throughout my pregnacy. I got married at 5 months pg and she was pressuring me to get married near where she lives (unsurprisingly, i had moved 150 miles away by then), where my younger sis had got married and how I should it mid week so it would be cheaper, not to book the small room even though there was only to be a small wedding. I'm so angry at myself that I just wanted to please her, thinking my wedding day would be special to her I suppose. She was making all sorts of demands that I was getting really upset so my DH suggested that we just married somewhere near where we actually live and somewhere that meant something to us and if she's can't come, then so be it. It was such a relief to throw the shackles off. We ended up with the wedding we wanted and no, she didn't attend as it was "too far away, too much hassle".
Did I mentioned she is an alcoholic? Not that she'll admit it. Booze seems to enable her to re-write history and conveniently forget how horrible she is. She encourages my younger sister to cheat on her husband and to staty at hers over the weekend (with the kids) so they can drink. Unfortunately, my sister is now just like her, a "mini-mum".
The final straw came for me when she started treating my DS differently from my siblings' children. I tried to exlpain to her how I feel, how I felt about the past and how she was / is with me but all she did was bitch with my younger sister behind my back about me. I then cut off all contact with her and haven't spoke for over 2 years. I've recently moved so she knows nothing about that.
I could go on and on with examples littered throughout my life. I've had to be a bit detached writing this just to get it out as it's so emotional.
I think it all resurfaced for me when I has DS. He is the absolute centre of my world and I love him to pieces. For a long time I felt there must have been something wrong with me why she didn't love me like that but with the help of MN I've slowly realised that it isn't me, it's her. She made choices in her life but doesn't want to accept responsibility. I'm just worried that I'll end up like her, that it's somehow genetic and end up hurting my son emotionally.