My question involves criminal law for the state of: california
I was at a local beer event and was walking to my cab when I remembered I left my brewery posters on an outside table. Me and my friend turned around and walked back to the gate where a security guard stopped us and said we couldn't go any further. I explained I left my posters on a nearby table and asked if I could grab them he said no. So I said can I have someone grab them for me when he responded with you better just walk away now. I replied are you serious right now I just want to grab my posters. He then head butted me and punched me in the face. My friend ran in between us and starting asking whats going on and telling him to stop. The security guard then tripped over something and fell and as that was happening my friend was grabbed and thrown to the ground and then I was grabbed and thrown down as well smacking my head on the concrete. At this point I just laid on the ground
saying I'm not resisting why are you doing this to us. And he grabbed my head and started rubbing the side of my head into the concrete to the point of making my skull bleed and me to have a bald patch. He then turned my head and began smashing my face in my blood pile making me drink my own blood. He sat on me doing this for what felt like 15 minutes until the police arrived. The officer grabbed me took me to his car and searched me. He then handcuffed me and put me in the back seat of his cruiser and took me to the hospital. I was there for an hour and then taken to jail.
Now they are charging me with assault and battery as well as being drunk in public.
I never laid a hand on him or made a motion to.
I feel like I am the victim yet I was told the security guard acted in his right and I feel like that is not the case any help would be greatly appreciated.

