I had an alcoholic mother. She sounds a lot like his mother. I went to therapy for four years. It helped a lot. With the background you describe, he can expect a long time in therapy.

Don't reward him because he had an intro with a therapist. Big deal! See if he actually goes to therapy, week in and week out, for many, many weeks. See if he actually changes.

In the mean time, don't wait for him. If guys come along that interest you, go out with them. Be open to other people. See where life leads you. Don't tie yourself to him.