AITA For Yelling At My Son For Telling My Other Son To Kill Himself?

I have 2 sons, 15 and 13. The 13 Year old is severely autistic, while my 15 year old is not autistic (these facts are important to the story as it explains why my youngest son was acting like this)<br><br>My youngest son has severe meltdowns, sometimes over minor things. He also is prone to screaming & hitting (though he has gotten a lot better with these things) and he gets frustrated when people do not listen to him.<br><br>I want to preface here that my oldest son has always been a loving and understanding brother. He has never had an issue with his brother being autistic and he has always been willing to cater to his needs.<br><br>Tonight me and my husband were out and we got home a little late. My husband went to check on the kids and he came back a few minutes after and told me that our youngest son had thrown a glass of milk at our oldest son and that he was furious when my husband told him to clean it up. I tried talking to him and he refused to clean it up until I told him to go to bed and that tomorrow he has to do all of the chores. He then got mad and went into my oldest sons room and started hitting him and screaming at him.<br><br>This is where the situation got verybad. My oldest son then yelled back at him and said he didn't care and to kill himself.<br><br>The situation was so bad to me that I was furious that my oldest son told his brother to kill himself. He knows how much it upsets him when he says things like this. We then both made him clean up the spill his brother had made earlier and then we grounded him and took his phone for the rest of the night.<br><br>I am getting worried that I overreacted on this and punished him for the wrong reasons. Was I in the wrong here?