Funerals are not good for anyone. Most people are 'on edge' beforehand, for various reasons.
Perhaps if you try to concentrate on your breathing. Deep breaths in, slow breaths out.
Whatever happens, you are not responsible for anyone in your family, or their actions. We all know we can't choose our family. If they say anything 'judgy' just walk away. Don't respond or interact in anyway. Your inlaw family can only form opinions about you by your own actions and words.
My sympathy to your husband and you on your loss.