What if I bar my mother in law from my husbands funeral?
Are you kidding? Do you not like your mother in law?
I don't want to see her face, she made life miserable for my husband and I.
You have to put your differences aside and allow your mother in law to be at her son's funeral.  If you try to bar her from your husbands funeral, it will make you look like a bad person and you will have a guilty conscious for the rest of your life.
I am a private person so nobody will know.
Even if there won't be many people there, you shouldn't deny her entrance. He was her son and she deserves to be there when he is laid to rest.