A canal mind cannot understand the things of the spirit.
Poster, I will not advice you stop sending her money. Please, keep sending her money but, always sanctify the money with the blood of Jesus Christ before you send it to her.
Also, don't sideline her, whenever she calls, answer her and always pray with her.
Your mother might have visited some secret places to do some things that has now backfired at her.
She needs help, spiritual help. She need to be taken to church unaware.
Yes, you can do it for her and your family. You already know where your problem is coming from; cutting her out of your life physically will not solve the problem, because you both are intertwined spiritually. She is your mother and you need solution, the solution is God.
Your mother need God to cut her completely from that secret cult. The people she might have make some kind of covenant with are still at work and you are not safe either.
Your eyes have been made open by God Almighty, it's time to tighten your girdle and go on a battle with the devil and all his agents but you must allow the Holy Trinity to take the lead.