I can relate to you. For years I was a secret drinker - at least a bottle of wine, if not more a night. I justified it because I was still functioning very highly, holding down a full time job and relationship and nobody around me was any the wiser.
It did mean I would turn down invites to events/dinenrs etc, because I knew there was a strong chance I'd have alcohol on me and couldn't drive.
Every morning I'd wake and vow I wouldn't drink that evening - and every day come 4pm I'd be in buying my bottle of wine
8 weeks ago something happened, and I stopped drinking. It wasn't really by choice, but it had to be done - and I can't believe how much has changed in such a short space of time. I don't need to hide bottles and chew gum to hide my breath and I can say yes to driving to most events.
I'm not saying it's easy - I'm seeing an addiction councillor, attending group meetings and having regular blood tests. I'm only 28, but I had done a decent amount of damage to my liver which thankfully has bounced back remarkably well in the 8 weeks I've been sober.
I think the blood test to check my liver gave me the wake up call I needed - so might be an idea to get it checked. I also live in a house with a partner who drinks, but that's his choice and I've made tis choice for me.
I'm not saying it'll be plain sailing - there have been a few times, and will be more where I'd love a glass - but like you, I don't know the one that's one too many, so for me, I can't say yes to that first one.
Regards groups, I was terrified when I went to my first one this week - but everyone is in the same boat - and everyone will have some stories you can relate to - you're not alone!