What do you tell family who tells you how to parent?

I'm a new mommy to a five month old baby. I know every one wants to give 'advice' to new mommies and how do you tell them to but out? Today we saw Gma and I was told I need to let her cry more. She was really tired and hungry and had spent two hours in the car and crying in gma's arms but she didn't want to hand her over. Then she went into when her son was a baby she always left him with people so that she wouldn't form an unhealthy attachment. I'm so mad!