I will be praying. Please get help for your cutting and suicidal thoughts. Talk to someone; a school counselor or trusted relative... There's a link in my signature, To Write Love on Her Arms, which is an organization that helps with said issues. I hope you'll check it out, look around, and maybe take some solace from Renee's story.
As far as the grief goes from the loss of your sister (as she's on this mission trip) I'll be praying for your adjustment in the coming days, and peace in knowing that God has not left you, and He loves you even in your fear and doubt.
Psalm 42 is a comfort to me in times of hardship... You're not alone in this.