Is the relationship I have with my friend, which goes beyond brotherly love to the point of infatuation and constant thoughts of him, considered desirable in Islam, or is it a wrongful relationship? And is what Sheikh Nabil Al-Awadi mentioned in his tape "A Love Story" about the condemnation of such relationships correct?

Allah forgives sins through His mercy. So, whoever errs out of ignorance, then repents and rectifies, Allah is Forgiving and Merciful. It is advised to treat brothers with kindness, respond to their ill-treatment with good, strive for their guidance, and increase in good deeds. This will mend the relationship with them and attract the love of people.