Marie, I had to do much the same thing with a good friend of mine many years ago. I was part of an intervention that "tricked" him into going into the hospital. He was so upset with me, felt so betrayed, and we've never been the same since. But he had to go, he was doing really weird things, like walking down a busy highway in the middle of the night with his pajamas on. He may not be talking to me anymore, but at least he's still alive now probably because we did intervene and get him the help he needed.

Your BIL sounded like he was getting much too close to a very dangerous precipice...my fear was that he would hurt someone if he didn't get help soon. My friend would not have hurt anyone, but would definitely have eventually hurt himself. Your BIL sounds like he might have gone the other way and hurt someone else. Hopefully, now, we'll never know for sure!