Where did my baby go and who is this?

I love my son to death. Do not get me wrong. I will do anything for my son and he is my entire world, but there are days where I swear that he is the devil or at least possessed by a demon. Tonight just happens to be one of those nights. My 63lbs 7 year just took it upon himself to attempt to whoop my ass. I don't mean in the cute "lets wrestle" way, I mean in the "look in my eyes and see darkness while I do everything in my power to inflict the most possible way because I hate you" way.

My son has been in and out of school all week due to not feeling well and needing to get an X-ray of his neck for his croup. He is a week behind on homework. So mommy (that's me) told him to do his homework since it was due tomorrow. Two hours later he is still not done. So I told him to get his ass out to my desk and work on his homework. He gets two math problems into it before the water works start. He loves math and he refuses to listen to me when I am trying to help him with the word problems. So after his "i am so tired I could fall asleep now" fit I tell him to get in the bedroom and give me my kindle back. He is so pissed off at me that he storms off into the bedroom and gets the kindle. I calmly tell him to set it on the chair, he proceeds to slam it on the chair, storm back to the bedroom and slam the door shut. OH HELL NO! We have upstairs neighbors, you do not slam doors. So I walk into the bedroom to get on him for slamming the door. As soon as I open the door I am met his an empty face and fists flying towards me. Followed by kicks, teeth, head butts, and pillows. I do not believe in spanking at all, but I spanked him on the butt two times for this. This went on for about 20 minutes until he got his pee pee stuck on my watch and hurt himself pretty bad. So he is not, thank the LORD, in his bed with ice on his crotch. Hopefully asleep.

My son has a ton of strength that comes out of nowhere when he gets like this, and it only happens when he reaches exhaustion, and that is not very often. I am not going to leave him alone in the room because he will destroy the room by throwing everything and knocking shit over. So the only thing I know to do is to hold his arms and legs as best as I can. He is strong enough to wriggle out of that though which means I still end up getting hurt. He ha drawn blood on me by doing this before. At one of the shelters in AZ my roommates were so scared of him like this they locked themselves in their room and called the office to get my mom to come help me.

Before my mom and son moved to AZ (I was there 4 months before them) my son attacked my mom (mind you he was 5 and she was 57) with a step stool, a plunger, a book, and anything else he could pick up. My mom called my dad and brother in tears because he hurt her very badly. My brother comes to the house pissed as all get out and asked my son what the hell he thought he was doing and asked him why he did it. My sons response was "because I am evil that's why." I did not find out about any of this until  MONTHS after they moved in with me and my aunt in AZ. I was livid. I have no idea why my son does this, what I can do to prevent it, how I can restrain him without hurting him or myself, or how to deal with the fact that my young child can turn on those he loves like this. My biggest fear is that he is going to snap like this with the wrong person, or he is never going to outgrow this and get locked up before he turns 13. I do not like being scared of my 7 year old, but that is what happened tonight. I was scared of my son.