Also, thanks for allowing for me to comment!

However, anger in nightmares is more likely a lot better than allowing oneself to get irrationally angry during the day, especially if they are only hurting themselves and being big babies (ahem…holding it in and being "the tough ones")! Many people often make the mistake of holding it in and mistake it for "letting go" when in fact they are simply pushing it down and storing it in a place we hope we'll never return to, not just simply turning it off and shipping to off to the dump. Which is one of reasons we get nightmares. The dreaming mind typically wants these things to leave, not be bundled up inside a box in our mental attic or emotional closet.

While we're awake, we might not be dealing with emotions properly, especially when it comes to the one you "love" (or only think you love) or the one who is mildly irritating, but in reality (while dreaming) you become aware that they are in fact very unhealthy for you to be around, or that maybe your love is loving love itself, not the person or that the person is deceptive, and not really in love with the person. The same with the controllable emotions like anger (or in my case) irrational anxieties!

Often, we tend to force those bad feelings (or even good feelings) out because we get too caught up in the illusion of the "real moment" of our sorrows, passions, frustrations etc and hold on to them, even if we, or someone around us knows it's unhealthy or a bad decision, allowing our biased or prejudice emotions to guide us instead of letting our intuition to take the lead and have a fair say. Yet while we dream, often the things we do not realize wake up and our true feelings come to life…or back from the dead!

I've found, for me, it is the most efficient way to be at one with my emotions, because, like you say, nightmares often try to tell you how to LET GO, not hold on.