How can I stop seeing my mom scream in pain?

I'm so very sorry that you have to endure this profoundly painful experience. I wish I could answer your question but maybe consider speaking with a therapist or clergy or grief support group. Please don't go through this alone. May you receive peace in your heart.

Grief Share is a group with meetings all over that many have found helpful in healing from a loss. I’m sorry you’ve experienced such a trauma and hope you’ll seek them or a similar group out and receive some wise counsel

Sorry for your loss. Are you seeing a therapist? Maybe do so? They should be able to help you with some techniques. Time is the best healer as well so it will get better with time. I love to find my own solutions so I would probably google for some advice too.