So the Lord spoke to Moses face to face, as a man speaks to his friend. Exodus 33:11a (NKJV)
Often we treat God as if He is far away. We feel like when we talk to Him we need to make sure we say the correct words and talk in the right manner. While it is true we need to show God reverence, we need to remember that we are also to give our earthly fathers similar reverential respect. God does not want us to be cold in our prayers; He wants us to be forthcoming and intimate. We should remember that we are talking to our Father, and He is our friend.
When discussing prayer I often encourage people to talk to God like they would talk to their earthly best friend. Let your guard down, open your heart and be brutally honest. If you are mad a God you might as well tell Him; He already knows. Holding that in will only cause you to harbor those feelings in your heart, which can lead to hatred and spite. If you are honest with God, it opens the conversation for Him to be honest with you. He is always right and you will have to eat some crow, but getting it in the open is the first step to fixing the issue.
God loves you with a fatherly passion that surpasses our capacity to love: unconditionally. Just like a good earthly father, He desires to hear from you often. God knows what is going on and He knows the thoughts and dealings of your heart, but He would really like to hear it from you. He desires a close personal relationship with you, and He cares about you. So do not be afraid to talk to Him, if you are off key with your conversation I assure you He will let you know. If you try to hide feelings and thoughts from God you will only stop Him from being able to fix the problem and cause your relationship to suffer.
If you will read in the Bible you will find that the people who were the closest to God, were the ones who were the most honest with Him; if they hurt they told Him, if they did not like His way they told Him, if they thought He was being unfair they told Him, etc. They held nothing back in their relationship with God.
I urge you to pour out your heart to God today. If you have been holding back hurt, anger, or anything else, get it out in the open with God. Tell Him exactly how you feel; do not be afraid, for He loves you.