I wish I had some advice on this, but I am really bad at this myself. I tend to bottle things up for way too long... Then, when the confrontation finally happens, I am so bent out of shape, that I have trouble communicating. Of course, afterwards I drive myself even crazier with all of the should-a, would-a's, could-a's... I can totally relate to how draining this can be.
The way to handle the conflict also has to do with the context - i.e. personal, work, kids... For me, handling conflict in things that deal with my kids (sports, school, issues w/ their friends) is the hardest. Next in line is dealing with conflict at work - because for me, being self employed, work is very personal. Too often, issues from work = sleepless nights...
I think Heather's advice on the "sandwich technique" is very good advice. Thank you Heather - I will have to remember that one!
