You are doing exactly what I have been doing for the last three years, ever since my DS1 was born. I suffered from crippling anxiety, probably PND too, and it was my way of coping after spending a full day looking after him. It relaxed me, made me feel like if I could get through the day until 5pm (my okay time to start!) I could reward myself with a bottle glass or two of wine.
I stopped when I was pregnant with DS2, but am back to the same pattern. I recognise it for what it is - my way of coping with the stress of looking after two small children, but it is a crap way of coping. It's not coping, it's avoiding coping.
A month ago my father, who spent most of his life as an alcohol abuser (which he used to hide from the things he didn't want to cope with), died from complications relating to his alcohol abuse. He lost everthing over the years because of it - his wife, his business, his home. At the end, he died alone , in debt. This is the end of the slippery slope you and I are on. You may never get to this point, but it is a sobering thought that you could.
This is why I have decided I need to do something about my drinking. I kept justifying that, although I drank every day, I didn't need it during the day, and I kept it within limits. So, I was not like my father (drunk all day every day till the alcohol ran out). I was lying to myself. You are doing the same.
I really don't like a lot of the advice that gets bandied about relating to alcohol and how to cut down. It all seems to focus on controlling your consumption with an iron will. Only drink on certain days of the week. Only drink a certain amount. Always drink a soft drink between alcoholic drinks. Have periods of abstinence. To me, all this does is focus your mind on how much you are not drinking, and we all know what happens when you feel deprived. You crave the thing even more.
I would recommend picking up a copy of one of these two books - Allen Carr's 'Easy Way to Control Alcohol' or Jason Vale's 'Kick the drink...Easily'. They are both based on the same premise, and are basically the same book (Vale worked with Carr, hence the similarity). It's all about seeing alcohol for what it is - a powerful drug with good marketing. It's the only socially acceptable drug that we are encouraged to use and have to justify not using (whilst also having to prove to everyone that we use it responsibly - which is a subjective judgement anyway, so pretty meaningless).
It explains (in a way that seems logical to me) that there really isn't any such thing as a non-alcoholic drinker and an alcoholic drinker. Anyone who drinks alcohol has fallen into the same trap, just to varying degrees. Think about it, no one on this thread can tell you if you are an alcoholic or not. According to AA, you would have to decide that for yourself. How bloody wishy washy and subjective is that. The fact is, like me, you drink to cope with stress, and un-wind at the end of the day. Your wife doesn't like it, and perhaps you wouldn't like it if you saw yourself with her eyes.
I hope this doesn't sound judgemental. I am currently trying to stop the cycle of drinking that I found myself in. I'm not fully there yet, but feel so much better when I don't drink. And, this is the key, so much better able to cope with two small children. I have more patience, I can connect with them more, and be more fun.
I also don't want them associating being a grown up with drinking, and my oldest was starting to do this ('When I'm a daddy, I can drink beer'). There have been too many people in my family lost young to alcohol misuse. I need to break this cycle. Maybe you do too?