Welcome to SR CoolRay
A great first step - going to Al-anon, second great step - finding SR. You are now on the path for recovery for yourself - good for you.
You will definitely be in for a bumpy ride, alcoholics dont like change. My AH 'reared up' when I started going to Al-anon and taking care of me. He was convinced that Al-anon was a cult, I was stupid for going, I was talking about him and he was paranoid, checking up on me. He was loosing his status quo and he didn't like that at all. They need to protect their drinking at all costs and change might interfere with that.
Your wife is threatening to leave because she doesn't want to loose her status quo and that is definitely normal behavior for an alcoholic. There is no such thing as 'normal' behavior with alcoholics by the way, they are completely unpredictable and unreasonable.
Form me it took 18months of therapy, Al-anon and almost daily SR to get to the point where I felt that I was making healthy choices for myself. Some of the SR family find peace quicker, some longer, but just starting on the journey of seeking help for yourself is fantastic.
Knowledge is power, so keep reading, keep posting and keep attending Al-anon as often as you need to. The hazy fog that surrounds you will start to lift.