I've been thinking quite a bit about emotions and guys, give me a chance here, but the two exact opposites are love and hate.  Hate is an odd emotion.  It shows up as anger but I was taught in my Christian Counseling courses that anger really is a secondary emotion.  After thinking long about this, I agree.  STICK WITH ME. 
Anger comes from either 1) you've been hurt  or 2) you've been disappointed unable to trust.  Then, you begin to feel anger from either of those two emotions.  Now, unchecked and undealt with, anger can turn to hatred, depression or numbness.  At all these points, YOU are the one paying the price....YOU!
Let’s go a little further.  Now, there can be Good Anger.  Yes, GOOD.  Good anger is righteous which makes us stand up and fight against what is truly wrong.  Let’s say abortion, stealing, bank robbery, Sept 9, 2011, etc.  I am angry at those actions, but I remember to separate the WHO from the DO and therefore, I can stay in the attitude of love and feel sorry praying for that the person did such an act.
Now, I, believe it or not was an extremely angry person from the age of 3 1/2 yrs.  I had been angry for so long that I had grown totally numb emotionally.  I grew up with the attitude, “Me & mine and I’m fine.  I don’t need anyone but me.”  Even a close family member kept trying to get through to me that I was so hard.  But, oddly, being hard was what got me the big jobs, the big pay, and big titles because I had no emotions and no mercy.  That’s what companies want in management position someone who is cool in the heat of battle, clear headed and doesn’t care to go for the throat in the deal.  God forgave me for that and changed me.  
Anger is, according to God, a recognized emotion.  He doesn’t deny it but He does tell us how to deal with it and the people that may be our source. Eph 4:26  Be you angry, and sin not: let not the sun go down upon your wrath: 27  Neither give place to the devil. 
Here’s how to deal with the anger if it’s a person: Luk 6:28  Bless them that curse you, and pray for them which despitefully use you.
Yes, even God is mentioned in the Bible as being angry but if you look closely, His anger is at the WRONG DOINGS of the people did and yes, there are consequences.  I’m not saying God is in Heaven waiting to hit you with a big stick when He gets angry at the wrong things in this world!  He is just, loving, kind, giving, merciful, long suffering, patient God!!  But being RIGHTEOUS & JUST means there must be consequences for wrong doing.  Just like a child being told not to touch a hot stove and they do.  Is the parent angry at the child? NO, BUT ANGRY AT THE HARM CAUSED FROM DISOBEDIANCE to a rule that was given to protect them.
Now, anger as I already stated, held in can cause depression.  Severe depression.  Guess what else medically it can do to YOU, not the person or situation you are angry at, YOU are the one being destroyed from the inside out!!  
TMJ. Medically, you can develop a severely painful disorder called TMJ which affects your jaw bones.  Your eating to stay healthy is now affected, speaking is difficult & painful, relationships wither due to lack of communication.  Not too mention your needed sleep.High blood pressure.  Now you heart as well as your kidneys, brain, and arteries are under attack from the anger.  You could develop heart attack. stroke, kidney failure, or arteries rupturing.Depression.  Well, if you’re lucky you’ll only be miserable every night and day or do the worst possible suicide.Asthma.  Yes, asthma.  You’re angry so your arteries, muscles, organs and bronchial tubes become inflamed because your body is producing huge amounts of the “fight or flight” chemical adrenaline and cortisone (steroid).  These are the two that also eat at your kidneys as well as your pancreas.Diabetes.  Yep, as I said in #4 those chemicals causes your pancreas to overproduce insulin which destroys your kidneys and help you develop diabetes because you are overworking the pancreas.Heart.  Yep, this too is effected.  Everything in the body is inter-connected.  Suddenly, your heart is pounding from all the adrenaline and cortisone (steroid).  It becomes enlarged and since you are producing all these horrible chemicals that God designed to be used for emergency only, you will develop arterial disease leading to a heart attack or stroke.Arterial Disease.  All the chemicals raging non stop from the anger now eats away at you interior veins and arteries.  Building up plaque (fatty gooey gunk) that will over time close the artery down bringing on a heart attack, stroke, or arterial rupture.Pancreas.  OK, now your poor pancreas has been working over-time producing adrenaline and cortisone during all this and finally quits or slows down.  You’re looking at having to use insulin or needing a possible organ transplant depending on what organ has also been affected (see list above.)Migraines.Chronic Fatigue Syndrome. You feel like every day you have the flu, you can’t move, you hurt, you can become bedridden.Ulcers.  Yes, you can die from ulcers as well as be miserable in the process. Arthritis. It too is an inflammatory disease process and mentioned in the Bible as a rotting of the bones. Pro 14:30  A sound heart (happy, peaceful) is the life of the flesh: but envy (or hatred) the rottenness of the bones.
These are NOT all the illnesses that can occur.  I’ve not even touched the relationships that are affected, the love you lose because of the anger, the sleepless nights, the joy of living you give up.  It’s like holding onto something you believe you truly deserve to hold onto (say a trunk of gold) and all the while it is what is dragging you to the depths of destruction to drown.
I know, I speak from experience.  Now, true, some of the above illness occur for other reasons, I’m just letting you know that ANGER can be the starting point for them.
Choose to truly examine your emotions.  Easy? NOPE!  But it’s better to dig up the root of the weed and destroy it than have the weed to continue to come back over and over.  Celebrate Recovery taught me to get to the bottom of my root.  FREEDOM AWAITED!  God’s way is the free best most joyful way.  I’ve lived both sides and I should know.  Ask, I’ll be honest with you.  I did my testimony for CR as part of the program.  Even my husband, until recently didn’t have a clue about how destructive my anger had become to myself but then, neither did I till God showed me.