I am sorry for your loss. The unexpected death of a loved just always leaves one in shock. And this just happened yesterday, so it’s all very fresh. I am so sorry you have to go through this mostly alone. However, death of a loved one is such that even though distraught, it as you say, still requiring you to function. And we try as best as we can. If at all possible, try call in the help of some of your family members, whom you think can help.

Make a cup of tea or your favourite beverage.
Make a list of all that you need to do, include small details, so that you can tick them off as you go along. top. It will help you not feel so overwhelmed. Put things like the will, the memorial towards the end as there other things that need your immediate attention. Calling the funeral home should be at or near the top. They will guide you with preparations. Also include calling the people you need to help. They can assist with your mom. They can also run errands if required. And don’t feel bad about this. People respond to death in a way that makes them want to help.
Try to sleep
Include eat breakfast, lunch and supper, even to drink water.

One day at a time. You’ll get through this.