jookbeard - this is easier for me to say than for you to do, but reading your last post this is my take. Bear in mind I do not know your situation and so I am shooting from the hip.
Don't go to her funeral. She didn't want you there. That is abnormal for any close relative to state. She sounds as if she was a most twisted individual. Maybe she did her own twisting or she built upon others twisting of her.I don't know.
It seems that her life was all about her. I've found some (not all) witnesses joined for what they could get. They obviously felt they deserved better than the rest of humanity. They deserved everlasting life; they deserved their parents being resurrected, in short they felt entitled. As the years slip by they get disappointed, depressed, negative, bitter and twisted.
She allied herself either tacitly or openly, I do not know which - with your abusive father - and she hated having been exposed - for her inaction or support of his behaviour - along with him.
If there is anyone who might be puzzled by your not attending that you care about you could send them a note saying that you would have gone to your mother's funeral as any normal loving human being would. But explain that (name the individual) told you that your mother did not want you there. Tell them you have no reason to doubt that individual's word and so have chosen to stay away.
HTH