Wow OMD. While reading that I felt so much anger for your "business partner" doing that to you. I am very happy that you got the job, but wow that sounded like a horrible situation to be in.
However, you should be extremely proud of yourself for not giving in to alcohol as it was essentially being forced down your throat. You have a tremendous amount of strength. You absolutely used those "sober muscles" that we always talk about. I hope that you are not mad at yourself. A few sips of wine that were essentially forced down your throat does not mean you had a lapse in sobriety. Instead it really is a testament to the strength that you have gained over the last four months to be able to only have a few sips.
I hope that you never have to be in a situation like that again. But I am very happy that you got the job. Sending good thoughts your way!