I empathize with the emotional turmoil struggling with a major change in belief. Mythology both ancient and modern is a facinating topic with many lifetimes of learning. Every day new insights and discoveries that better reveal the cult and cultures of the past and how these inform the present ones. Only when I allowed myself to deal with religion as a social phenomenon rather than a "machination" of the Devil, did I see my own religion as a small part of the larger whole. Many times expose' styled Christianity detractors make tha mistake of compiling simplified lists of parallels as if by the shear length of the list others would see what they see. The issue then becomes a challenge for the believers to compile lists of differences or unique aspects of their religion as they practice it. The larger issue is that religion is a part of a culture and everyone is as unique as the culture as a whole. New religions would not attract many converts if their beliefs and practice were identical to competing ones. No, just as the needs of the society changes, religion evolves and adapts. Even as it does is always retains sometimes awkward vestigial imagery and story that betray it's less sophisticated past. Judaism is a clasic example of a cult caught between adapting to the needs of a modern society and clinging to the ancient adaptations of Palestinian, Persian and Babylonian mythology that served to motivate and inspire past generations. What makes the issue rather ironic is that it is the insistance upon literalness that creates this tension and yet the ancients themselves were not literalists! History and morality were all told through story and symbolism. Many ancient peoples were not so foolish as to believe giants, talking snakes and world wide floods had taken place in their recent history, at least certainly not the authors of the tales. To understand what I mean, talk to a Hindu worshiper and try to understand the power of their acknowledged myths have in their lives. They believe that the message is revealed within the myth, the myth is not understood as history, textbook style anyway. Hinduism is one of the few faiths that has amazingly retained it's ancient flavor while yet enabling it's people to become a technologically advance society. Sadly the less educated in any society have always been given to credulity.
A study of the texual cues and mythemes makes very obvious the OT is a compilation of stories and myths, some very ancient, some less so, some with historical elements others not. Sections were adapted and compiled more or less by a particular sect as a powerful tool for inspiring national identity and galvanizing particular sectatarian views. As it was inherited by later generations furthur adaptations were necessary. It was not deceipt or malice that motivated its editors and author just politics and religion as it is and has always been.
Posters such as Leolia and Narkisos have been involved in rather advanced topics in this area in the past. I'd strongly endorse reading the topics they have started or been involved in in the research and belief sections of this forum.
If you ask yourself honestly, do you really think all the stories in the Bible really took place. I doubt it, noone does. We tend to be selective and emphasize what we do find credible and try to forget the doubts. Honestly, that is true of every believer. That will continue to work for some people but I suspect not you. Coming to terms with that reality is not so much a decision as an epiphany.