Seriously. It’s a little strange and looks like a controlling issue from the FILs end. There’s not even space for me in my parents house when I visit them anymore. My old room has became an office and becomes my guest room but the closets and drawers are filled with my dads stuff now. I always live out of my suitcases because its not my space anymore and if I need to, I just hang my extra clothes in the corner behind his stuff. I wouldn’t move it even on my longer visits even though that was my old room. Even my mom on her visits in my home since we live in an apartment for now lives out of her suitcase and partly shares with me if she has to. To avoid a mess, I move things around but that’s all really all I can do. It’s not even a big deal but FIL is totally making it an issue because he thinks he can.
It does show FIL has his own complexes and seems to be very unwilling to happily adjust in his sons home and is more concerned with creating trouble than being a simple guest. But op your reaction is all wrong, stop getting emotional and letting it bother you.