I yelled at my mom

I have a five year autistic son. He doesn’t understand danger and elopes pretty frequently. I am constantly in a state of panic that he is going to get out and die. It’s a reality that I live with. I have locks in place but I always know where he is. Anyway today my mom was over along with my older brother and nephews and niece. I had to put my chickens in since it was getting dark and asked my mom to watch my son. She said yes. As I’m putting the chickens away, I see my son leave the house. I wait for my mom to come out and get him but she doesn’t. I go and grab him so he’s with my while I put the chickens away. I felt absolutely livid cause this happened a few weeks ago when I asked her to watch him. He left the house without her knowing and I found him outside. Anyway, so I go in and unload on her “Mom why aren’t you watching him?!” “I didn’t hear the door open.” “You’re supposed to be watching him!” That’s when my brother said to me sarcastically, “isn’t terrible when your mother doesn’t follow your orders?” I yelled at him too and they both left upset with me. Ughhh I just feel so frustrated that I can’t depend on anyone but also it isn’t their problem. I maybe shouldn’t have yelled. I don’t feel like apologizing but maybe I should? Any insight please 😔