Keegan-Michael Key's Estranged Wife Says Divorce Physically Destroying Her

Keegan-Michael Key's estranged wife says his ending of their 17-year marriage was so unexpected, it's causing her serious health problems ... in addition to leaving her in financial ruin.

Cynthia Blaise says she's suffering from severe depression, anxiety, hair and weight loss and PTSD ... according to new legal docs, obtained by TMZ. She says she's been taking 5 different meds since the 2015 divorce filing.

Blaise says she financially supported him early in their marriage with her work as a Hollywood dialect coach -- and even when his career took off, she was at his beck and call.

She says Key made way more than her in the final years of their marriage -- including a $1.2 mil Toyota endorsement deal -- but she's fallen on financial hardship since the split ... due to giving up her career.