MIL again- why do i bother?

i had abit of a argument with my MIL because she criticizes me through my daughter we went there today for fathers day (australia) and it was a personal attack on me from both my MIL and FIL - now things we going fine until she came home and started making smart **** comments about myself and the way i do things with my child. such as my FIL said my daughter had a big head i of course said she didn't then he said to his wife " the mother said the kid has a fat head" the MIL said "well id rather have a fat head then be ugly like some " referring that it was coming from my daughters mouth. i just said " i beg your pardon" she ignored me and walked off. then as we were leaving i said to my daughter mucking around " what are you giving mum daggers for ?" MIL said "well her father cant f**king feed her can he" in the nastiest tone i have heard her speak yet. i ignored her and left and i will not be returning up there for a very long time. my hubby didn't even say anything to her which upset me as well. and her hubby was egging her on with smart a**e remarks, on my mothering skills. but they need to remember that i am the child mother not them.