My H told his mother a bunch of lying, blaming crap to make himself look good because he was ASHAMED to have failed at our relationship and wanted someone to pin it on. That's what your H did too. So yes, your MIL is WW a bit, but she thinks what she thinks for a reason... the pessimistic depressive who went home trying to save face and BLAMED most of it on you.
That said, she is a good source of the most exaggerated info., which he may actually believe at this time. Go have dinner, be pleasant, listen A LOT, keep your opinions to yourself at dinner, and go home and take notes.
