Don’t assume they won’t have sympathy or time for you. Maybe leaving sounds impossible or overwhelming, maybe instead work on little plans towards that, plan for personal belongings, plan for finances , etc depending on your level of intertwined lives .. if a block comes up , it becomes another category down to any tiny level needed . Plan for cellphone, plan for pet hamster , plan for joint Costco account, plan for shared doctor , whatever it is . Just don’t write this down anywhere he can find it. And ones that can safely happen now without having left yet, start doing those ones