MIL physically held my arms to keep me from getting to son

My MIL thinks I am too much of a helicopter parent. I’m not I just don’t trust her. Well tonight at Thanksgiving dinner my son who is 2 was playing with his brother, sister and their other sister (brother and sister are my stepkids). I couldn’t see my son from the other side of the room but I heard them say “Be careful.” Well mother in law stood in front of me and held me by my arms from going closer to see what was happening. “He needs to get into trouble. Leave him alone.” And she would not get out of my way no matter what I said. It really pissed me off. My husband who I haven’t talked to about it yet, will definitely say I am overreacting and that she ‘was just screwing around.’’s my baby. That boy is my world. I should not have a person standing between us especially when he is only 2. What do you ladies think? Am I over reacting?