Tom Sandoval's comparison between George Floyd's murder and his cheating scandal's not just drawing ire from fans ... it's also pissing off the mother of George's young daughter.

Roxie Washington, -- who shares 10-year-old Gianna with George -- tells TMZ ... she's not super familiar with "Vanderpump Rules" and doesn't even know who Tom Sandoval is ... she does say he has to be off his rocker to compare his own personal issues to Floyd's death.

ICYMI ... Sandoval sat down for an interview with the New York Times where he said, "I’m not a pop-culture historian really but I witnessed the O.J. Simpson thing and George Floyd and all these big things, which is really weird to compare this to that, I think, but do you think in a weird way it’s a little bit the same?"

Well, Roxie tells us she finds Sandoval's comment flat-out stupid ... adding he and his ex-GF, Ariana Madix, are still alive ... so him trying to compare his situation to George's just isn't reasonable, nor is it even in the same ballpark.

Even though she's not familiar with "Scandoval" ... Roxie says from what she can gather -- Tom's a grown-ass man who's just gone through a breakup ... not a child -- like her daughter, whose dad isn't coming home.

RW didn't just blast TS for comparing his situation to George's death either -- adding Nicole Brown Simpson's dead too, so she finds it just as disrespectful for Sandoval to invoke her name as well.

Roxie says Tom needs to go repeat that "dumb s***" in a mirror ... telling us his comment reflects horrible things Gianna hears from some classmates. She also says this is on the same level of absurdity as comments Kanye West made in the past. So, yeah ... she's kinda comparing Tom to that.

Remember ... in 2022, Kanye claimed Floyd died from a drug overdose/preexisting conditions, and Roxie threatened to sue KW on behalf of her daughter -- though it's unclear if she ever filed a lawsuit.