1. AA isn't for everyone, but there are secular options. If you're in the US the meetings might end with a prayer, and that doesn't sit well with non-believers. I didn't go to AA, but I might have if I felt I was struggling.
2. Secrecy is the friend of the addict. Try not to get boxed into storing everything up and suffering from the strain of not being able to unburden. Your journey is yours to live. 'Privacy' is often an excuse to keep drinking in secret. If you need to unburden to a friend or family member, that's your right. From what you say in point 3, his drinking problem must be obvious to your social circle.
3. This is a hard one, but it's not you who should feel embarrassed. I do understand you're coping with the consequences though. If you're isolating yourself for reasons of embarrassment or fear then maybe you should consider the viability of your relationship, or socialise on your own.