I am so sorry for your loss, but your Mom is no longer in pain and her suffering is over. I lost my Mother to lung cancer 17yrs ago and to this day I still miss her almost every day. The only thing that time does is ease the pain of loss a bit. What keeps me going is knowing that one day I will see her again. Hopefully that will give you some comfort at this terrible time.
I will keep you in my prayers for the Lord to give you strenght to get through this.
Lois