Never stay angry..
It is a waste of time and we have so much better things to do then be angry..it is a waste.
It is ok to get angry and be angry..but it has its purpose and a time.
I can remember being so mad at him...2 hours later he commented on my grumpiness and I replied...well jeeesh I am still mad! He simply said "Why"...Hmmmm well I don't know arent you...He smiled and said "Yep I was mad 2 hours ago but we resolved it and I want to spend my time enjoying being with you...not being mad."
If everything in life could resolve itself so quickly and people move on with out angry...
I once learned about anger in a psych and communications class..it is a 2nd emotion. For being a 2nd emotion it sure can cause alot of harm and hurt.
We don't just get mad...mad or anger comes from another emotion. Hurt, disappointment, fear, let down, sad, and from there you begin to build anger and being mad...
Life can change so quickly and the next day is never the same as the first....not alot of room for anger if you want to make memories and enjoy the moment...so let it go after a while..dont hold on to it...resolve it and move on