Telling one person
You do not have to tell the whole family or give exact figures on day one. One person is enough to change a great deal: somebody to message when the urge arrives, and in front of whom the behaviour stops being invisible.
The reaction people fear — the judgement, the disappointment — is usually a good deal worse in the imagination than in reality. And whoever does react badly is almost never the only option available.
Support groups
Member associations run free groups, in person and online, both for the person gambling and for their family. You do not have to be in an extreme situation to attend.
What a group offers that no website can is that nobody there has to explain the basics. That saves an enormous amount of energy.
Professional help
Gambling disorder has treatment with an evidence base, principally cognitive behavioural therapy, and it is covered by public health services. Associations also provide it free.
Asking for professional help does not mean the situation is severe. It means you would rather not find out how far it can go.
If thoughts of harming yourself appear at any point, that is not part of the process and it should not wait. Crisis lines are free and available around the clock.
Relapses are part of the process
Most recovery processes include relapses. A relapse does not erase what came before or prove you cannot do it: it shows the plan had a gap that something slipped through.
What helps after a relapse is not guilt but the specific question: which barrier failed, and how does it get closed? That is why the plan has a review date.
The takeaway: You have finished the route. What remains is not on this website: it is in completing the first item of your plan today, not tomorrow.