so can any mommas tell me why it's bad to microwave breast milk?? I know a few already. I'm watching…

so can any mommas tell me why it's bad to microwave breast milk?? I know a few already. I'm watching my sisters kids and her boyfriend started being an ass hole because I wouldn't heat the 2.5 week Olds bottle in the microwave because I know you're not supposed to heat it in the microwave. my sister would have a cow if she knew he heated her bottle in the microwave. I'm here because my sister doesn't think he can handle it on his own (for obvious reasons) I didn't even argue with him and he threatened to call cops to have me removed. lol Really? talk about a physco.