Aaron Phypers is blasting estranged wife Denise Richards for showing up at his house to grab a dog and causing all sorts of drama -- he says she never cared for the doggies in the first place ... and claims she left him and his elderly parents to care for all of the animals.

The “RHOBH” alum’s attorney claimed Richards “entered the home to retrieve her dogs after learning that Mr. Phypers had put down one of her other dogs without her knowledge