For 20 years I was so careful to hide my drug use from EVERYONE. I produced my own, used alone, isolated to large extent, while being responsible to my work and obligations so no-one knew, of course so to be able to use without being restricted. I think that's a primary fear for not telling others about one's use, being "watched" or otherwise provoking suspicion about use. If others know, you're not so free to indulge freely.
The week I filed for divorce I then told my family about the addiction, the drug treatment program a year earlier, the trying unsuccessfully to get clean, difficult in a marriage with a partner who used (some of) the drugs I did, the mess I'd created.
They were relieved I told them. It helped them understand why I was so aloof, so distant, so private.
I'm glad they know, have known for 2 years. But until I was serious about quitting, I wouldn't have told them. It would have caused a lot of conflict. They would have "interfered" with my using. I'd have become even more distant, perhaps worse.
But yes, a very personal decision, as others say here. Good luck making your choice