My mom has dementia. She's violent, hurting me and herself, and breaking stuff every day. Where do we go from here?

Yes, call 911 and have them take her to the hospital. While she is there, work with the hospital's discharge planner/social worker. Tell her or him that your mother cannot safely be sent home, and that you are not safe due to her violence.

Do you want to share more about your situation? Do you and she live together, and if so, in whose home?

Sometimes this can happen if an elder has an Urinary Tract Infection (UTI), make sure your Mom is tested.

Yes, others are correct. Please call EMS and have mom transported to hospital.
Call Adult Protective Services in your area if this isn't possible.

Call 911 any time she is violent. Don’t tell the EMT it’s dementia just tell them she’s being violent. They will bring her to the hospital for evaluation. You should never be caring for someone who is abusing you.