I'm an alcoholic 7.5 months sober and nobody irl has any idea
Why have you kept this accomplishment a secret?
I didn't want anyone to find out who I am, in particular my boss.
Your struggles are your own and you do not owe anyone an explanation about anything that is none of their business. If you are not comfortable talking to someone about it, you're not entitled to say a word about it.
I think i'll go ahead and tell someone after this chit-chat.
I am glad that you want to tell someone. I think that telling someone is a good way to help yourself stay committed to the sobriety.