Grieving. Any tips!

My Aunt passed away suddenly from a heart attack at 43 years old.

I'm only 20 and I don't know how to deal with grief

She was more than just an aunt she was my nannie and my best friend we lived with her for years and the whole family is broken

I am so depressed and I went from compulsively eating to not eating at all.... I can't sleep been up for close to 24 hours...

I'm seeing a grief counselor on Thursday any tips until then??