When employees leave?

When employees leave I immediately want to either begin to look at their bad side, feel revengeful or begin to blame myself for doing something to make this happen. Being in the business I have dealt with this issue several times and I want to have a better approach to this.

C staff leaving
T how could you leave
F how will I survive without them, I have to train all over again, and my business will be impacted hard.
A started sharing my frustration with other people and eventually posting and finding new people
R Find someone

I have come a long way in moving from negative thoughts to action but I don’t want to feel the betrayal and anger towards people leaving as they were good for when I hired them.