I've been grieving a big loss, but I have hope.
First, I'll list some help from the bible, then some resources below.
1 Thessalonians 4:13-18 ESV
But we do not want you to be uninformed, brothers, about those who are asleep, that you may not grieve as others do who have no hope. For since we believe that Jesus died and rose again, even so, through Jesus, God will bring with him those who have fallen asleep. For this we declare to you by a word from the Lord, that we who are alive, who are left until the coming of the Lord, will not precede those who have fallen asleep. For the Lord himself will descend from heaven with a cry of command, with the voice of an archangel, and with the sound of the trumpet of God. And the dead in Christ will rise first. Then we who are alive, who are left, will be caught up together with them in the clouds to meet the Lord in the air, and so we will always be with the Lord. Therefore encourage one another with these words.
https://bible.com/bible/59/1th.4.13-18.ESV
And...
Matthew 5:4 ESV
“Blessed are those who mourn, for they shall be comforted.
https://bible.com/bible/59/mat.5.4.ESV
Here are some resources I've found helpful and others that have suggested.
Griefshare.org - a Christian based ministry offered by many churches.
A few books you might find helpful:
John Eldredge: "All Things New"
Randy Alcorn: "Heaven"
Raymond R. Mitsch and Lynn Brookside: "Grieving the Loss of Someone You Love"
Suggested for Children:
A great book for kids is the invisible string. They actually have a workbook that goes along with it.
There is another book... called the rabbit listened. It's not as much focused on losing the person as it is on how to express your grief. It really helps them know what are helpful and useful ways of expressing their grief to others.