<human>: Can you give me a shortened version of the text?

Saturday night was my best friends birthday and because my house is bigger than hers she asked if the party could take place here. So I spoke to mom and dad about it and they agreed. 

My brother was helping me set up the party, he did all the heavy lifting. My brother almost all ways wears this necklace, the necklace that our grandpa left to him when he died. The necklace is basically a gold chain with a painted black shark tooth. He only takes it off to go shower and leave it hanging on his bed frame. 

My brother was not attending the party, he had a date. He had asked this girl out and she said yes. He was taking her out to see the darkness I think or Captain America then the two were going out to eat.  

In the excitement of it he forgot to put his necklace on. I think they had a good time, they spoke for long period of time on the phone today.  

Last night the party was fun and my friend had a good time. When my brother got home he went up to his room. He stayed there until everyone went home. I was sitting in my room later on. He walked in and he tossed his necklace on the bed. The tooth was completely broken, he looked at me and said " who did it". I told him I did not know and he said " Well you better find out real fucking quick, I want to know who came upstairs and I want to know by Monday"

He has not spoken to me since, he is furious and he has 'forbidden'me having any friends over or he will make their life a living hell until he knows the guilty party. 

I just don't know what to do, mom and dad are going to Cleveland tomorrow and are leaving me here with him. He is so angry and I don't know what to do.
<bot>: Someone broke my brothers angry and he is furious. He has told me to find the guilty party. He has threatened to make my friends life a living hell, if any of them come over before I find the guilty party.