Hello Kell C,
You can Let Go and Let God, as they say in Al-Anon, (God is however you define your higher power). Your friend is going to meetings, working with a sponsor, and he could probably even do the recommended 90 meetings in 90 days, given the space and time (no relationship distractions, no family commitments in his life presently), and the support you fear he does not have in his world he WILL find.
Sometimes new people in 12 Step groups can be judgemental about whether they "fit" and are skeptical about whether "those people" can be of help to them. I experienced a bit of that when I first attended Al-Anon decades ago. I had recently finished graduate school and there I was, sitting in a church basement with a lot of people who were very different from me, for sure. Very different. It's what happens when you are a newcomer to 12-Step.
But here's what a person needs to do. He or she needs to start giving to the group in useful ways. Set up the chairs or make the coffee before the meeting. Fold up the chairs after the meeting. Volunteer to pick up literature for the meeting. Put the sign out by the road for the meeting. Suit up, show up, help out, and we get to feel comfortable. Not so alone. Traumatic feelings begin to ease.
And this option is COMPLETELY available to your friend. And he might be slightly drunk in meetings. Or drink as soon as he hits the parking lot. But those people will always be there. They will not judge. They will listen. For one hour, he can retrieve some self-esteem. And he can make the coffee and set out the chairs.
So: you don't need to consider yourself his only hope or his only real friend. He doesn't have to get sober tomorrow or next week or this year. But he can go to meetings of his own free will and find fellowship and keep trying. If he has a sweet kind-hearted girlfriend who gives him the alternative of skipping meetings and instead sitting on a warm sofa listening to his woes or his dreams or his alcoholic delusions, he may well choose that instead of a meeting. Instead of building a relationship with a sponsor.
Honestly, it's okay to move to one side and let him find his people.
You can wish him well. You can even in your heart, for now, hope that in the future you may reunite if he achieves significant long-term sobriety. Often people simply can't wait, they want everything to happen on their time, completely disregarding God's time. And Fate. And lessons which have been set in someone's path.
I would avoid the phone calls, if he tries to stay connected, he is in no shape for meaningful dialogue. And might not remember the next day there ever had been a phone call. My exAH forgot a lot of things, in his disease. But you can place him in the care of his higher power. And maybe he will call his sponsor instead.
Wishing you peace of mind. Maybe try a few different Al-Anon meetings, too. So you can have a little help realizing that peace of mind.