Ecc 7:2
It is better to go to the house of
mourning, than to go to the house of feasting: for that
is the end of all men; and the living will lay
it to his heart.
Ecc 7:3
Sorrow is better than laughter: for by the
sadness of the countenance the heart is made better.
Ecc 7:4
The heart of the wise
is in the house of
mourning; but the heart of fools
is in the house of mirth.
Solomon said that it is better to go to the house of mourning, or to a wake or a funeral, than to go to the house of feasting because that is the end of all men. In other words, we (except for those who are yet alive and are "caught up" when Christ returns) will all die one day, and as we see the dead body lying in a casket, we should lay it to heart, or we should realize that our numbers will be called one day as well. Solomon linked this mourning with sorrow, but he said that it is better than laughter because by the sadness of our countenances our hearts are made better. How so? Because when somebody else dies, it makes us think about our own mortality, and it tends to shift our focuses away from that which is temporary to that which is eternal.
Phl 2:25
Yet I supposed it necessary to send to you Epaphroditus, my brother, and companion in labour, and fellowsoldier, but your messenger, and he that ministered to my wants.
Phl 2:26
For he longed after you all, and was full of heaviness, because that
ye had heard that he had been sick.
Phl 2:27
For indeed he was sick nigh unto death: but God had mercy on him; and not on him only, but on me also, lest I should have sorrow upon sorrow.
Phl 2:28
I sent him therefore the more carefully, that, when ye see him again, ye may rejoice, and that I may be the less sorrowful.
Phl 2:29
Receive him therefore in the Lord with all gladness; and hold such in reputation:
Phl 2:30
Because for the work of Christ
he was nigh unto death, not regarding his life, to supply your lack of service toward me.
When Epaphroditus was nigh unto death, God not only had mercy on him by sparing his life, but on Paul also lest he should have sorrow upon sorrow. In other words, Paul would have sorrowed had Epaphroditus died. Of course, as you said in your OP, Paul would have sorrowed with hope that he would see his brother in the Lord again at the resurrection of the just.
Rev 21:3
And I heard a great voice out of heaven saying, Behold, the tabernacle of God
is with men, and he will dwell with them, and they shall be his people, and God himself shall be with them,
and be their God.
Rev 21:4
And
God shall wipe away all tears from their eyes; and there shall be no more death, neither sorrow, nor crying, neither shall there be any more pain: for the former things are passed away.
When the tabernacle of God comes to dwell with men in the new heaven, new earth, and new Jerusalem, God will wipe away all tears, and there shall be no more sorrow, nor crying, nor pain, and all of these things will disappear when there shall be no more death, so they all seemed to be linked to death.
Anyhow, sorrowing, crying, weeping, and mourning are normal when a loved one dies. Thankfully, your mother was a Christian, so you do have a hope of seeing her again one day. I just lost a niece about two weeks ago, and it is unlikely that she was saved, so I cannot honestly say that I have such a hope where she is concerned. I had not spoken to her for a while before her death, so, hopefully, she got right with the Lord before she passed away. Just try to focus a lot on your eternal hope, and not too much on your temporary loss. I know, from what you have described elsewhere, that it has caused you a lot of natural problems too. I will pray that God supplies all of your natural needs and that he also strengthens you by his Spirit according to his riches in glory by Christ Jesus.
Phl 4:19
But my God shall supply all your need according to his riches in glory by Christ Jesus.
Eph 3:16
That he would grant you, according to the riches of his glory, to be strengthened with might by his Spirit in the inner man;