Anger is the face of grief that is in my opinion most common, especially if the loss was sudden or unexpected. Although it is identified as one of the stages of grief it is now understood that not everyone goes through these various stages of grief. Anger may not be a part of everyones grieving experience. It may instead manifest itself as us lashing out at someone in frustration. Regardless it is a possibility, and an emotion that can quickly arise within us, one which is extremely powerful and intense. It is less felt and expressed. I felt it when realization hit, that I had lost my brother forever. The anger was unlike any feeling of anger I had had in the past.  Getting angry does not necessarily mean one will lose control and do the unimaginable. I never did lose control, but I was still very angry at my brother, I was mad at myself. I was angry at the driver who struck him, and, I was angry at God for allowing it to happen.
I am sure nothing is wrong with being angry with your self and others, as anger itself is not sinful. But is it okay to be angry with God? To answer the question let us use our handbook the scripture. The bible speaks of several people in both in the Old and New Testament who expressed anger towards God. David often, openly expressed anger towards God in the book of Psalms. He wondered if God had left him alone and to the mercy of his foes. In the midst of his despair he cried out to God. Jonah also expressed anger (though unjustified) towards God. The question remains. It is okay to be angry with God?
In the New Testament there are examples of individuals being angry and even displaying anger towards God but the Bible also is very clear that we should not dwell on our anger as it could harm us or cause us to harm others. In Ephesians, we are cautioned by our heavenly father to avoid anger. In the book of Proverbs too it states that nobody likes to hang around angry people. What benefit does anger actually have? In general it causes stress, anxiety and can lead to medical problems. The bible says be anxious for nothing. If we really stop and reflect, our anger, stress, or frustration does nothing to change what is. We need to just cast our cares upon Him. Easier said than done? I know…
The fact is though that the only person who can help us is our heavenly father. What he thinks of us is what really matters in the grand scheme of things is the creator and Lord of All. What does he think of us? He loves us unconditionally. He loves when we pour out our hearts filled with emotion to him.  Anger is an emotion. We must however remember that this same God toward whom we are expressing our anger is the one who loves us the most in this life. We may not understand why we are going through a loss of any kind, but we can trust that God will be there for us and will work all things out for our good.
Are you kidding me? You may say. How can loss workout for any kind of good? That is the thing about God and His ways, they are beyond our human understanding. What is interesting to note is that we may start out being angry with the one who created us, but in the long run He will never turn His back on us, even if we try to turn away from Him. In Psalms although David started out angry with God he always ended up trusting, giving thanks, praising and rejoicing.
This is why in Psalms  he said:
But I have trusted in thy lovingkindness; My heart shall rejoice in they salvation. I will sing unto Jehovah, Because he hath dealt bountifully with me.
Below are scripture for your reference:
Old Testament
Psalm 22:1
My God, my God, why have you forsaken me? Why art thou so far from helping me, and from the words of my groaning?
Psalm 13:1-4
How long, O Jehovah? wilt though forget me for ever? How long wilt thou hide thy face from me? How long shall I take counsel in my soul, Having sorrow in my heart all they day? How long shall mine enemy be exalted over me? Consider and answer me, O Jehovah my God: Lighten mine eyes, lest I sleep the sleep of death; Lest mine enemy say, I have prevailed against him; Lest mine adversaries rejoice when I am moved.
Jonah 4:1
But it displeased Jonah exceedingly, and he was very angry.
Jonah 4:4
Then said the Lord, Doest thou well to be angry?
Job 3:3a
May the day of my birth perish.
Proverbs 14:17
He that is soon angry dealeth foolishly: and a man of wicked devices is hated.
Proverbs 22:24
It is better to dwell in the wilderness, than with a contentious and an angry woman.
New Testament
Ephesians 4:26
Be ye angry, and sin not; let not the sun go down upon your wrath.