*hug* listen, people are always going to try to put others down to ease their own insecurities and feed their own bias. You know that you're a good mother, and if she can't see that it's her problem. My sil is about 12 years older than me and some of the crap that came out of her mouth was ridiculous. She has low self esteem and i think putting me down made her feel better about herself, but guess what the proof is in the pudding, my girls are now 10 and 7, top of their classes, well rounded beautiful girls and though she still makes comments that they are 'wild' etc, anyone can see that I've done a good job. Don't let her spoil you or kiddo's relationship with your nan, extended family are important in your childs life. Totally ignore snide remarks, be mature and it'll pee her off but it will make her look like the petty person she is. Start just saying calmly "we'll have to agree to disagree", "each to their own" and " thanks for the advice but I'm happy that this is the right thing for us". If she doesn't take the hint, just walk away. She'll get the message. Good luck x