That was a low blow as well. Bellatrix immediately tensed, and her hands clutched her arms so hard her knuckles turned white. She wanted to hit him. More than anything she wanted to hit him.
"You don't get to mention him. You left him, just like you left all of us, and if you love your dear Potters so much, why don't you go join them?" She turned back towards Sirius, her eyes mere slits.