I've heard that the hardest losses are the ones that come at a time when you would naturally be breaking away, if everything had stayed on track. Thus, parents divorcing when one is 21, or in your case a death at around that time, are harder to get past because you were interrupted in your natural trajectory of separation from the parent and didn't get a chance to live that natural flow yourself, it was taken from you. I always thought this was interesting because it was true for me, my parents divorced when I was in my early 20s and it took me over a decade to get used to it and stop wishing they were together.
In your shoes, I would see a therapist and discuss everything. Your mom wouldn't want this life for you, she would encourage you to get better. A good therapist will help a lot. Between talk therapy and maybe antidepressants for a period of time so you can lift out of the gloom, you might find a lot of other things to live for and enjoy again.
I understand complety how you feel, I to lost my mother 4 years ago this month.I really felt all thwe same things you mention & didnt think I could even breathe without her.I still have to try to block her out of my mind just to make it through many days & I am sure that will never change.Life as I knew it has been forever changed.
But please honey dont loose your hope & faith keep them alive until you see her again.Love really never dies & God promises us that.Those are the 2 things you really need to make it through.I f you need to talk I am here.
Bless you,
Lisa