No doubt you have empathy for the man, I totally understand that. Just be sure you don't throw yourself under the bus in the process.
You are looking out for him, as I mentioned above, it's important to look out for yourself as well.
If he was sending you texts asking for your opinion or trying to get perspective or your guidance on where he can get help (has he ever asked for help?) something like that, that's one thing, that's not what this is.
The next time he starts with the abusive texting I would really hope you will call the RCMP. He needs professional help, you can't save him from himself.