Is disappointment a valid feeling?

We all want certain things in life or have certain expectations of others in our lives.  Disappointment is a valid feeling but a negative one.  It is an emotion that if we do not deal with it accordingly it can turn into anger.
We often say or hear that people aren't perfect and we know this too well because we ourselves are far from perfect, but it can be heartbreaking when you place your trust on someone that ends up disappointing you. 
The only way I can see fit to deal with this is to forgive.  Forgiveness is the most crucial step for healing because it brings peace to our mind.  It isn't a sin to go through the process of being upset with someone that has let you down but it can become a sin to allow ourselves to go from upset to angry. 
When we become angry we stop trusting God for his Justice.  In order not to allow disappointment to remain in us we need to do the following:

• Admit to God that and why we are disappointment (confessing our feelings to someone else will help us clear our head and our heart)
• Forgive.  Forgiveness is the hardest thing to do because it makes us feel we are not validating the wrong that was done to us but is essential for us to be freed from this wrong
• Don't try to fix things.  If you're like me you feel that you need to fix every single issue that rises in your life.  Take a step back, take a deep breath and think.  Don't make any rush decisions that you may regret later.
• Try to see why God is allowing this to happen.  Try to look for the purpose in this.  God might be trying to show you something you would otherwise not see unless going through this experience
• Trust God and wait on His timing! 

Trusting God and waiting on Him has been one of the hardest things I've had to do besides forgiving.  However, I've realized that when I try to fix things I normally become frustrated.  When I wait on God for His timing I feel peace when I see Him fixing what needs to be fixed.