Anna Faris is firing back after her former showrunner threw some serious shade her way in his new memoir ... and she says Chuck Lorre's casting dig was painful to read.

Anna is responding to Chuck revealing he felt vindicated by doubting her casting on "Mom," with the actress saying ... "Yikes. Yes, I read a few things. I really didn't see that coming. Of course it hurts."

As you know, Chuck says his "initial reluctance" to cast Anna in the starring role of "Mom" was "in fact, correct" following her departure at the end of Season 7.

Chuck claims the "mysterious reasons" why Anna left the series after Season 7 "were not mysterious to anyone on the show."

Anna says ... "Chuck gave me a job I loved, and for seven years I never took a day of it for granted. I'm proud of what we made together, and nothing changes how grateful I am for those people and those years."

She adds ... "I've been sober for a year and a half. I was on a show about recovery and then I lived it. Now I'm healthy, I'm working, and I'm happier than I've been in a long time."

Anna's friends had her back after Chuck's curt critiques ... slamming his insults as "s****y," considering the actress gave 7 years of her life to the series.