This is absolutely true for me, too. When my mother lay dying in a hospital in 2012, my ex-husband informed me (through his father...he didn't even have the guts to talk to me himself) that he believed I was lying about it to get out of a court date, and would not agree to a continuance. My former father-in-law said something like my ex-husband "wasn't doing this to be a jerk, but because 'I tend to be hysterical and emotional about things'." So this 37-year old (at the time) woman had to call my FATHER, and have him call my 45-year old (at the time) ex-husband's FATHER to "convince" them that my mother was indeed on her death bed. *sigh* Now, there was that added layer of ex-spouse animosity in there, too...it wasn't just a case of my feelings being discounted because I'm emotional. Just because I cry easily, and had been put through the wringer by those people for YEARS, I was accused of lying. But yeah...and I can assure everyone that my mother did indeed pass away the night before we were supposed to have that court hearing.
And of course my AH discounts my feelings all the time. Like all of us, I could write a thousand-page book about it. But it's that experience with my (non A) ex-husband that stands out most for me.