Get over it

So my kids are at that age where they think that just becasue a friend was mean to them it's the end of the world. I hate that. And how do you tell them that it's not as big of a deal as it seems right now? I mean they think that they will never get over it. I know how they feel, I've been there. How can you make them see that there is a whole lot more world out there left to live and they may not even remember what happened in like ten years. It frustrates me cuz I'm scared they will base decisions on how they feel right now. Sometimes I wonder how my children have lived this long. With me as a mother. :)