"What irked me about this comment was that my MIL implied that this whole thing is my fault and that all of the issues were on my W's side."
No she didn't imply that it was your fault. Go back and reread what you wrote. She just told you the concerns the W told her. She didn't blame you. Unless she came out and told you that it was "YOUR FAULT BECAUSE, ETC."
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.