Will everyone know my financial affairs and how much money I lost?

No. Arbitration is private and not open to the press. Only the parties and those representing the parties will generally know what is filed with the arbitration forum. Of course, there is no guarantee that one party will keep all the information confidential, but it is a common practice for parties in an arbitration to enter into a confidentiality agreement to further try and protect the privacy of everyone involved. 

Privacy and confidentiality can be of particular concern to those clients that live and work in small communities, or are concerned that others may learn of the arbitration, their personal financial condition, or the losses they incurred from trusting one of the local, well-known and respected financial professionals.  Many prospective clients feel guilty or ashamed of letting their accounts be improperly invested, but the legal duties are on the financial professional, not the client.  These fears and concerns are generally overcome and mitigated by the confidential nature of arbitration.  Often, nobody ever learns of the case, and pragmatically, most brokers and advisers don't advertise the fact they have had claims made against them from others in the community.