Go back to your room. Who is she to tell you you aren't allowed in HER? bedroom anymore? If the last you checked your name is on the deed and mortgage (though don't say it like that to her because it will get you nowhere), then go back. Because that is not a healthy separation for YOU. You will probably just end up resenting her more and more for relegating you to your son's room. That's not healthy for you or your son. In fact, leave that room for your son's benefit if nothing else. What's he supposed to think when he sees that?
I don't believe in stirring up unecessary arguments out of pride or anger, but this is a matter of right and wrong and appropriate separation from your son. I know you're resistant to tell her no on this, but if you don't....I would be shocked like I've never been shocked by anything if it actually helps your sitch.
In answer to your question, this is a terrible boundary to not set for yourself, that being your own sleeping arrangements.
M-34 XW-32 D-7 Found OM's presence 4/09 Separated 12/09 Divorced 8/10 GREAT relationship as coparents since 8/10