Dinner with the ex

Tonight I'm supposed to have dinner with the ex that I have talked about on here the most.  I still have issues concerning her but I'm trying to retain a friendship with her because I know it's important to her.  But it still messes with my head.  We're supposed to have dinner in about 3 hours and the closer it gets to that time, the more I want to just cancel it.  Not sure if I should or not.  I want to take the high road and hope that it'll make me a better man but at the same time I don't want to get depressed again.  I've been very good about being depressed lately.  Haven't felt sad for about 3 weeks now.  But there's this fear that it will start me on another downward spiral.  Maybe I should cancel.  I don't know.  We'll see what happens.