i dont think you understand how guys work, if you tell him you want "Space" then he automatically jumps to the idea that you want to break up with him, this might devastate him. Give him something more specific than space,just say that you need a couple of days to relax alone, you need some time to chill, just be specific, otherwise he will think your doing something your not.
Make sure what you want is clear and set out clear guild lines for him so he knows exactly what you mean by "space". Whether it be physical or communication wise and what exactly you want him to stop doing.
if he isn't giving you space, space yourself out from him. talk to him still but if he follows you everywhere just say ti him straight... "I want space" it works, just don't say it too aggressively or he'll get mad