Mother in law

My mil criticizes & complains about my parenting skills every chance she gets & it really hurts my feelings. She said she rather tell me than me hearing it from a stranger. She said she's not doing it to hurt my feelings, she telling me so I'll get better at it as a parent. She said she'll be doing this until her grandkids are older. My fiancee actually agrees with her. Have any of you dealt with is? What did you do? How did you manage to handle it?