I've been reading everything, but didn't want to add on since you're getting so much good advice. fwiw, SD, my position with BIL would be this:
"BIL, I'm so horribly sad for everything that is going on. I've been advised not to discuss this with anyone, and all I can tell you -- and you're going to have to trust me on this -- is that the truth will come out in due time. I HAVE NEVER LIED TO YOU, you know that, and I never will. The truth will come out, and you will eventually understand why I'm having to protect myself."
I told my in-laws something similar, altho my situation was a little different. The point is, there is a way to "keep mum" legally, while also showing your honesty and sincerity, I believe, IF this is a person of character (and it sounds like he is).
Have a safe flight. You and my family are HARD in my prayers, SD. Godspeed. You are doing well, considering.
