It’s been interesting to watch the typical prgression of this thread from stock answers that don’t apply to your questions (which are excellent, btw your catholic instructors should be congratulated for developing enough interest in the faith to question it so precisely), through to various emotional/authoritarian approaches: appeals to guilt, threats of exclusion or future punishment, derision and so on, hoping to convince you to end your questioning so they can stop thinking about questions they can’t answer.
A few have made honest attempts to provide you with answers or point you to resources-Church Militant’s suggestion seems especially good.
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My own recommendation to you is a book by Jaroslav Pelikan: Mary Through the Centuries: Her Place in the History of Culture* (1996) Yale U. Press, ISBN 0-300-07661-4
More of a history book than theology, it shows the development of various strains of marian thought and belief over history and provides ample references to documents that often get lost in current discussions.
As to the question of your eternal destiny: according to the catholic church your decision to leave is grave matter, thus a possible basis for mortal sin. I’m sure your studies have informed you of all the conditions necessary for mortal sin, and you will have to judge whether you fulfill them since a brief set of posts on an internet forum don’t permit a decision on the conditions of sufficient reflection and free will.
Of course, at a meta level to this discussion you will also have to deicde whether you accept the church’s teaching about leaving being grave matter and whether the three conditions are correct, but you asked for the catholic position.