I agree with Draco that it could have gone much, much worse. She could have drawn her wand. She could have yelled. she could have tried harder to manipulate him. She could have found a more effective way and succeeded!

And do you really think the place where she raised her only child holds no happy memories for her now? I don't see that. Draco did not use a mocking or condescending tone when he called her Mummy twice. He wants to have a good relationship with her.