once you separate they wont be with one parent all the time. by separating physically, clearly there will be division of the Dc time between two parents so no one parent is going to have the children all of the time.
there is an apparent discrepancy between him being violent abusive etcetetc but "open door access" and a 65:35 split. if he was that bad, then you would have no open door and would be insisting on supervised contact in a contact centre.
so if you accept that he can be with the DC quite happily 35% of the time and can manage that quite well, then you cant then say you should have sole residence and that he is too abusive to be around the dc.
you also need clear evidence of his ill health, stress etc. does he accept he cant be with them due to stress? any parent shave stress/depression etc and dont have restricted access...i got supervised contact order initially because there were SS and police reports my ex had been violent during his severe mh episodes and had severe MH breakdown including hospital admission. and a police report including his admitting to smashing things up, etc.
later on as he took meds and improved his GP was very keen to say he was stable and that "depression" does not a bad parent make. uand this is the crux....you simply cannot tell a judge "he is too stressed to have the DC" - it would need to come from him and he is stating he is fine to have them living with him.... also surely moving out might stress him further?
unless he has been admitted to hospital with his stress and been treated in psych ward etc you really cant use it as valid argument against him having 50:50.
even with my exp's background and history, i have had a hard time getting people to listen sometimes...
go back to what is best for DC - you could say they love their house it's close to school, they can have their own rooms, it is best they stay there - but dont expect the judge to necessarily agree that you should be the one to reside there with them.
you could also suggest the kids stay in the house and you take it in turns with dad to stay here with them. there is a name for that I think ...
me and dc moved out - but it was to a better place with a garden they didnt have before...