I wonder Stormrider, if at least some of your situation is got to do with control? You seem like a really in charge, decisive person. Maybe a lot of your H`s trouble is feeling less in control himself?and with his overspending, apparent MLC behaviour and 180s he`s trying to assert himself? Maybe it would be a 180 for you not to try to control the separation either-let him do the deciding on whether you split or not.
I know the in limbo living together apart thing is difficult. I`m living it right now. But I wonder would actually splitting up make recovery of the M more difficult. You`ve made lots of changes already,sounds very like you`ve implemented the Last Resort Technique.
I would keep barreling on with preparation for the separation of course-which includes developing a network of friends as support for you, as well as sorting the financial side of things.All of this will serve you well anyhow if your M continues.