Detaching should be the goal. You need to detach so you can move your focus from your W to yourself. When to go dark? I can't answer that for you, it's something you need to determine for yourself. I would recommend rereading DR and see what it says. Perhaps others here can chime in.
GAL activities are VERY important. You need to be able to have a fulfilled life. Look, if you end up getting divorced, you'll be on your own and will need to rebuild your life. Why wait for that? Now is the time to become the best person you can be. Plus it keeps your body and mind otherwise occupied so you can't obsess on your sitch.
Golf sounds like a great GAL activity! With the summer coming up there will be lots of opportunity to play and you can easily go by yourself to the local course and join others to complete a foursome. What else have you always wanted to try or that you used to enjoy doing but have let slide? There are all kinds of groups you can join if you don't have friends to go out with.
Look, I literally only have two real friends where I live, one is married and one is engaged. I used to do just about everything with xBF and that was fine because we enjoyed hanging out together (despite what he said later ;)). Since this happened I have spent a lot of time those two friends who have totally welcomed me even though I'm now a single and not a couple. I've also reached out to some other acquaintances and hung out with them a few times.
I know doing things alone can be scary. I'm not really an outgoing person by nature. But I look at this sitch as a crossroads in my life. If I want to get more out of life then I have to put more into it. Here's an example. I have a single gf who lives in another state. We were talking on the phone one night and I mentioned that I bought myself a ticket to an upcoming concert. She said it's coming to her city too and she wanted to go but didn't have anyone to go with. I asked why she needed to go with anyone? This is something I want to do and don't want to miss out on just because I can't find someone to go with me. Doesn't mean I'm fearless about doing everything alone (I don't really like to go out to eat at nice restaurants by myself) but I have had some great experiences that start out alone so I'm willing to do more.
Getting off my soap box...
If you love somebody, set them free. http://tinyurl.com/2empx2g