Your brother sounds like he has some issues with your financial position and ability to run a company. From my similar experience, my brother became totally two faced, even to the point of making up stories, and continued his character assasination on me for years before I found out, (or had proof).
In that time period, he was able to isolate my mother from any association with me or my family, many elder friends I had over the years suddenly stopped association (not all at once though) and he was stealing from the company, (not petty theft.)
In fact, one brother working for me for years called one night and told me that my brother was screwing me over, and I thanked him for reporting it to me. I would say to "proceed carefully", whatever you say or don't say, he will make something up to continue his character assasination. There is no telling what he has told people.
Your brother now has control over what people hear of "what you are saying" and of your "spiritual condition" as noted with your FB friends, and can and will make up anything necessary to advance his agenda, most likely destroying you. It is only starting with the FB "friends".
And witnesses talk about the anger issues and mental disease of apostates.