Disappointment

So I have a question for you all... What do you do when other people disappoint you?  How do you deal with the situation?  How do you deal with the person/people?  How do you deal with the fallout and aftermath? 

I'm in a very interesting situation.  I've been disappointed by a lot of people in my life-time.  Usually, I'm just able to tell the person, resolve the situation and move on with new knowledge and let's be honest, generally a little less trust. 

Usually these situation deal directly with me and my involvement.  Someone didn't do what they said they would, someone didn't keep their word, some one's behavior was unacceptable.  

I'm also very loyal, or so I've been told.  I don't like people speaking badly of my friends, or anyone really.  (side note, venting is a whole other thing... Limit your venting and ensure the person your venting to can keep their mouth closed!)  I will try and stay out of it.  Speaking badly of others just makes the speaker look bad and mean spirited and those listening look just as foolish.

The current situation has to do with many people and multiple occasions.  I'm involved in a small number of them, but tried to just let them go, because individually they're insignificant.  However, the more I'm hearing about additional incidents involving my friends, the more upset I've become that I didn't confront my issues, because maybe if I had these additional incidents wouldn't have happened. So now, I feel very stuck.  I can't bring up and confront the offenders with my own issues, because they happened months ago.  I can't bring up other people's issues because it's really none of my business and they confided in me.  And, I can't not do anything because it's killing me inside to continue to witness my friends getting hurt and bullied.  

So, here I sit.  

Hating every aspect of my life when it comes to having to interact with these particular people that have disappointed me.  I can't avoid them.  My current life situation dictates that I deal with them on a fairly regular basis, and like it.  I'm not that good at "fake it 'til you make it!" although that is my motto. 

Maybe I shouldn't have had such high expectations.  Maybe I shouldn't have dealt with my individual issues with them in silence.  Maybe I should confront them now.  Maybe, maybe, maybe... ugh!  I really am at a loss here.  

Advice?  

And I swear if your advice is get over myself, I may hurt you if you don't tell me how to get over myself with detailed, step-by-step directions.