Interesting about the MIL. My MIL and I actually got along fine... in fact, she used to tell me and others that I was "the angel who came into her son's life", that I "brought him back" to his family, etc. H has always had a difficult R with her and has always commented on how much she "loved" me.
She never cleaved from either son too well, but has always had a much more attached R with BIL, which is going through exactly what you described with my poor SIL. She's a pretty controlling personality, makes lots of snide remarks, etc. I always ignored that because it was never directed at me.
Oddly, she seems more attached to my H than ever before.
All along she has emphatically denied her son has any depression at all, even when he's been saying otherwise. Of course she has also adamantly denied any use of the word "affair"... and suggested that other family members "support" H by not being friendly with me. It's all a bit odd to me... not how my family operates anyway.
About the intuition, it's weird. I do sometimes seem to have uncanny intuition about some things...always have. Don't always listen to it, though I am working on that.