I do not have children so have never had to handle this kind of thing, but I am an adult child of an alcoholic and have a great appreciation for how my mother always handled conversations with me about my father. One, she never badmouthed my dad to us kids. Two, she always described his problem as a disease. She never complained to us or let us see her emotions about what she was going through as the spouse of an alcoholic, or what he was doing. She always taught us to respect him as our father, with the understanding that he is human.
Not sure if any of this helps but thought I'd share just in case. Take care.