It is Normal actually as your son has felt jealous about the new Baby, and because you have got into a Battle of wills it has continued . You say you fight with him every 5 mins, stop doing that , try to figure out the trigger point for the tantrums before they happen, set some Bounderies and use the time out system, Banish the spanking idea it does not work and teaches him its okay to hit others.Your problem is one of Parent/Child interaction,thats not working.From when you read this post, no more fights ,,back off, dont do it ,if he yells that okay ,let him, place a chair somewhere quiet tell him to stay on it till he is quiet and sorry, it can be a mat or a bean bag even,he will yell, he will get off , do not yell back at him, say nothing ,take him back on to the chair over and over ,till he is quiet and sorry then a big Hug .Give him more attention now ,and make sure he knows he is loved as much as the 2 year old, if there is a Dad there ask him to help with lots of Games and guy stuff.No choices of clothes put out the ones he has to wear,Do the same with the sleeping take him into his room after reading stories say goodnight and leave the room, he will come out take him back .let him yell at the bottom of the stairs ,if you keep giving in he is getting mixed Messages, consistancy is the key.