I was fortunate enough not to ever have experienced that type of abuse, so I'm speaking as an observer, but I don't think that your experience will have been the formative event that defined you being trans. It probably will have influenced how strongly dysphoric you are and obviously will have left you with major issues towards males. Not cause though sweetie.
The problem is that your negative experiences back then feature so prominently in your mind that they drown out any good experiences and feelings you might've had as a young child. You need to replace those bad memories with good ones, positive things that build you up rather than breaking you down. You need to try and access your true, genuine self and see what that person was like.
There's a technique some schools of psychology and self-development use called Remembering. It's really simple - all you do to start with is at random pick a feeling, a smell, an image or something, and look for a time in your past that you might have experienced something like that. Do so by vividly visualising what you've chosen while you try to think of an earlier point of experience. When you do recall something, don't just write it down and move on. Instead, really visualise that experience. Try to add as much detail as you can to the picture. Now move back from it, try to be an objective observer of the events that memory contain. Judge it and the actors in it like you might the characters in a book or a movie. Believe me, it puts alot of things in your past and in your present in perspective. It defuses alot of blame you might feel towards yourself as well as others, and with hindsight you can more clearly see the threads of cause and effect that made you who you are. As you dig up and relive more and more old memories, those will in turn be associated with yet other memories, until you start to build up a complete history of yourself and who you were at various points in your life.
Our brains store and retrieve information via association, which is why smelling cinnamon can bring up powerful memories of early christmasses, for example, or feeling down and depressed can bring all your past downs come tumbling out at you as well. So this is a powerful technique for digging up forgotten and repressed things.
When I accepted that I might be trans, I also wondered whether it might've been caused by events from my own past rather than fundamentally be a part of who I am. So I determined to find out. My memories of anything past the last year or so were really poor, but I'd come across this technique, and tried it. I just sat writing and visualising, day in and day out, for almost two months, and by the end of it I'd accessed some of my very earliest experiences and feelings from when I was two, three, four years old. Where at one point I'd thought my feelings of being female were associated with events from when I was in primary school, doing this exercise showed that they'd been around from my earliest memories at two, three years old in how I acted, who I emulated, how I saw myself. I had not recognised them as such because I only really became aware of the differences in the sexes in primary school, and so that was where those feelings had ended up attaching themselves. Being able to look back as an outside observer, I could go and reattach those feelings where they belonged.
We reject and repress so much because we try to forget painful things, or try to fit in, or try to live up to expectations we have of ourselves or others have of us. But you're at your most genuine and truthful when you are that young, before experiences and your own ego start reorganising our psyches. Hopefully you can detach the feelings you have around the trauma of your own childhood and place them where they belong.
Mina.