I don't believe in God because of something that happened to me. I was molested at the age of 12 when I knew nothing about sex or any of that. It happened with a 60 year old man. He had a drinking problem, and I did not understand anything about it. I was told to go down there and take care of his daughter when he was drunk. His daughter was 6 years old and needed someone to watch her. He would try touching me and I would resign myself to it because I had this strange feeling it wrong. So how come my grandmother said I brought it onto myself to let that happen? I was 12! I am sick of hearing it was a test! Also I was then raped by a friend in high school. Both times I did not ask for these things to happen.
I don't know know very many people who ask for tragedies and disasters to happen in their lives. The reason your grandmother blames you is because she doesn't want to face the real fact. I assume she is the one who sent you down and she, as an adult, knew better than to send a 12 year old girl alone to deal with a drunk man. Putting the burden on you allows her to avoid her guilt.
What the drunk, your grandmother, and your friend all did were things contrary to what God said was proper behavior. So why does the existence of people who are evil lead you to conclude that the essense of good (God) does not exist? Seems to me that we need more people following God so that less evil is done and when it is done that it is properly punished.