I’m sorry to learn of this sad news. There is no harm and possibly great benefit in talking to a mental health professional so I suggest you set up and appointment asap.
Your points 1 and 2 are good ideas. Yes to both.
No to 3, and I think you know that. To play devil’s advocate, college admissions officers have read everything under the sun: Loss of loved ones, loss of pets, instability, terrible home life, medical issues, mental health issues, and some truly heartbreaking and disturbing personal circumstances. Things so profoundly tragic that they sometimes have to stop reading.
The loss of your great aunt is a personal tragedy, but if you mention to AO’s that it’s affected your GPA in a few days, that is going to come across as sounding very petty and also raise a red flag. They can’t admit people because they feel sorry for them. A HUGE a number of students have tragedies in their lives. They want kids who can forge ahead, despite the tragedies. Why?
You’re going to go to college, where you will be plunged into a very different environment. You will have a new room, bed, food, faces, and none of the home comforts. There will be much higher expectations from professors than you had in high school. They like resiliency because they know that some students will have a difficult time coping with all the changes. Some students won’t be able to cope. They will leave. Colleges want students who will stay. So don’t give them reasons to say no to you.
Grieve your aunt, because that’s part of the process of healing. Make a bit of an extra effort to stay on top of your school work and your activities. You will get through this time.
P.S.
It seems you were pretty close to your great aunt, but many schools have rules about students taking time off only for immediate family members. I’m sure your teacher wasn’t trying to be unfeeling, but probably felt her hands were tied by rules.