Does divorce occur if one is excessively prone to self-doubt and utters, "Divorce be upon me" or "She is unlawful to me" before consummation?

It is clear from your question that the entire matter is [a result of] waswasah (whispering from Satan/obsessive thoughts), which does not lead to divorce or prohibition. So, ignore these obsessive thoughts and beware of giving in to them, for their consequences are dire. Seek Allah's help and occupy your time with what benefits you.