Save those emails and print them out. Have you started a journal yet, logging all contact between you? He's being careful here, but saying he hopes you die, so he's avoiding using words that might get him in trouble, but still, it's better to be careful here.
And yah, block him.
Regarding telling him about the divorce, he was going to blow his lid anyway, whether you told him or he just got served. Let him have his hissy fit. He's not your problem any longer.