I need a little help /talking to /kick up the bum! And I know mumsnetters are the masters of all of the above 
I'll try (and fail) to keep the background brief!
I told my husband in February, that I want to separate. He's a 'functioning alcoholic' - and various other issues financial abuse, emotional abuse etc. Despite my best efforts to help him overcome his issues, all that happened is he got worse anyway and I developed major co-dependency issues (textbook case, I know this now!) He's on a path to self destruction that I can't save him from and I know that our young DS and I need to live separately from him to prevent further damage to me or DS.
Anyway, since that first conversation, I have had to have the same conversation again, because - after an initial phase of him being remorseful, threatening suicide and life not being worth living etc., he has moved onto be so completely immersed in denial that he just won't accept it's over (predictable really but I wasn't expecting it!) So we went through it all again and I reiterated that there is no going back and nothing to save in terms of 'us'.
Despite it being spelled out to him he's saying he can't let me go etc and just going on as normal (just without physical contact and not doing things together).
I want him to move out. Our home, mortgage etc is all in my name, I pay most of the bills anyway and am primary carer for our DS, and so for me and DS to be the ones to move out would be a lot more difficult, expensive, and not to mention completely unsettling for DS (unjust also!) I can buy him out.
He earns a lot more than me so could afford to set himself up easily (for now, until he eventually allows his drinking to take his job as well. I don't want this to be my problem).
The problem is, how do I ask him to move out?! I already know the obvious answer is to tell him to move out!! But I'm finding this as big a hurdle as the first time I told him we were over 
and I think I just need to hear it from outside my own head to help me actually action it.
With co-dependency it's very difficult to stop doing the things I've always done, protecting everyone from his mess, providing way more than I should etc. I'm very accustomed to burying myself and just having to react to him. Although I've managed to detach emotionally, I'm still being a doormat. I'm also scared of him to a point, at some point he will get angry and he's the master of deflecting all blame and issues onto others.
Every day that passes is another day wasted that I am not yet on my path to recovery from this toxic relationship.
I need to grow a backbone and get on with telling him to go (and then crack on with divorce proceedings if he refuses?) Any practical advice on how I actually do this would be gratefully received!