Your movements are interrupting me

I just follow the seatplan, but a friend of mine suddenly chose to sit on mine. On the chair and table I always sit on, to just do what needs to be done. I looked right, seeing him sitting there and the chair next to him being empty. Is it going to be weird if I ask her if we could've swept seats? Will I start it with a joke? Or will I drop the truth? I couldn't settle my mind, it's processing slowly. I didn't even look left if there next to my friend were chairs avaible. So I just dropped my backpack under the table and sat next to him. I didn't put my school equipment to the side because of him, my heart wasn't beating anymore, and I didn't feel the need to cry anymore. I looked to the side sometimes when he wrote loudly on his i-pad, but I felt nothing sitting there. When he comes I push my chair aside, take my bag which fell infront of him, and answer with a nodd. Because he wouldn't pick it up, Because I still want to handle it respectful, because I want to keep it short. I skip your leg and don't wait for your response.