The problem person here is you.
This will be tough to read. Because your parents probably made the same mistake you are making with your kid, you may not have the resilience necessary to take the following advice. This may be hard to do because it will require you to take responsibility for doing something that is hurtful to your kid.
In a culture that has fully committed itself to putting blame on everything and everyone else but ourselves, actually taking responsibility for our own behavior and then fixing said behavior has become an activity from a bygone era.
On the off chance that you are still with me, let’s move forward.
Human beings learn resilience by having to be resilient. When you don’t allow kids the opportunity to suffer through tough situations, they will never learn to handle tough situations. Your son crying over an ice cream cone mishap or being devastated by not getting a part in “Fiddler on the Roof” is not a bad thing. It’s a great thing. It’s the only thing that will teach your son how to toughen up enough to be a good student, be employable, and be a successful person in any endeavor.
This is not a “parenting” thing, this is a life thing.
It is ludicrous to say that an 8-year-old is not “ready” for the rejection of not getting a part in a play. It seems that your definition of being “ready” for something is that a person is ready for something when it will cause minimal or no pain to that person. If that were true, none of us would ever be “ready” for anything. This just isn’t how the world works.
You seem to believe that the rejection of not getting a part in a play will cause lasting or permanent damage to your kid. I must say, this is a uniquely western, first-world perspective. Things like not getting a part in a play will not cause lasting or permanent damage to your kid. Things like a drone dropping a bomb on your family’s home will have that effect.
Here’s the simple equation to allow your child to be tough enough to live a successful life in the real world:
Trying Something Difficult + Failure + Suffering + Parent Empathy + Hugs = Growth and Grit
Here is how it would look in real life:
Kid: I didn't get the part! BWAAAAAAAAHHHHH! (Kid completely breaks down)
Kid Whisperer: Oh, man. This is really hard. (Kid Whisperer picks the quivering mass (Kid) off the floor and gives Kid a big hug) I just love you so much and I know that you are strong enough to get through this.
Kid Whisperer pats Kid's back while Kid continues to lose it.
The universe and its laws are doing the teaching here. Kids get better and stronger when they have to. Just get out of the universe’s way and love your kid while he is suffering in order to allow him to learn and grow.