If you include him as non accompanying, they will still want his medicals and background checks but it's a good way if you are not sure yet if you are heading for divorce. You could still provide separation documents later on. If you know at this point that you are heading for divorce, you might as well do the legal separation and try to get him removed from your application. However, keep in mind that if you get him removed from your application and he doesn't get medicals and background checks and later you get your PR and then reconcile, you will not be able to sponsor him based on that you got him removed from your file and he was not examined.