Sibling Rivalry Show Down

Currently I am trying to survive the sibling rivalry in my household. Ethan had no problem with his sisters until they became mobile. Once they started crawling the jealousy set in and he also became very territorial. Now that they are walking and fighting back it has been an ultimate fighting show down and I am the referee. He hits, pushes and takes their toys away. Now I know that many will say this is normal but when you are living it it is living hell. I have tried every punishment in the book, except spanking, and he does not care. I feel like I spend my days just yelling. I do not want to raise my kids this way. So I am on a mission to chill out and remember that he is just displaying insecurity through aggression. I love him and I hope this time will pass soon for both our sakes. Any one suffering the same fate out there?