I'm going to do a 'do as I say, not as I do', okay?
A big part, perhaps the biggest part, of detaching, is maintaining your own mood where YOU want it to be - peaceful, relaxed, pleasant, whatever - regardless of how your H behaves.
One day at a time - try not to look into the future (more than you have to to consider finances, etc.). Today he is still there and you are having good times together occasionally. And you have friends to go out with, which is a great thing.
Try to think of your H as a roommate. Try to give him exactly as much headspace as you would someone you know casually.
Force yourself to focus on work - if you get into something interesting, it will give your mind a rest for a while.
We're all tired of this - it's difficult and painful and feels like it will never end. Like everything else, this too shall pass and in the meantime, it's spring and the world is still a wonderful place to be.
