Most likely they are jealous of you, or your husband, or both.
I have the exact same issue, and I am strongly out-numbered. I am fortunate enough to live far away from them, and it is still hurtful. Keep in mind that maintaining a peaceful demeanor while they show their “true colors”, it will be obvious to all involved, especially your child, what the correct and righteous behavior is.
Best of luck to you, Dear.
Love and Light to Your Family.