If a fiduciary relationship is found to exist between parties, the trusted party is indeed held to a higher that ordinary standard or "degree of care" and responsibility.   Even though your relationship seems muddled in familial waters, it may have been a breach of his duty to advise what was going on with you financially to others.  There exists in fiduciary relationships a component of confidentiality along with loyalty in representing you.  Seek consultation from an attorney in your area regarding the matter and what your options are as to damages, etc.  The matter is in most cases a tort but in some a breach of contract claim.  Good luck.