The song shouldn't be "Big Girls Don't Cry" it should be "Big Girls Don't Get Angry" because we're supposed to stuff it till we burst and still come back smiling. Sometimes my friends are amazed at how I can spout forth my venomous tirades and end up laughing because I seem as though I've gone round the bend to a land far, far away never to return. What they don't realize is that I know I am angry over certain things and consider it my right as a human being to express that anger in an appropriate manner from time to time.
Also, releasing anger in the form of "venting" can actually act as a literal valve, releasing the energy of whatever it was you were so upset about and preventing you from doing something you may regret later. For all the lovely talk of processing and working through, sometimes women, just as men, need to work out, punch it out, shout it out, or talk it out, expletives included, until they feel better.
To be honest about your anger allows you to be honest about your love, too. If you are a woman or girl who refuses to acknowledge your own anger, how can you ever be honest about your positive feelings? As the owner of your body, mind, and spirit, you are in charge of your feelings. To ignore, judge or denigrate your own feelings and push them further and further away will not allow you to bask in the true beauty of the good times - your negative feelings will follow you like a lonely sister.
There is some credence to the fact that concentrating on negative feelings can promote them. However, acknowledging real anger is far different from this - it involves trust; not only of others who you may need to bounce ideas off of; but of yourself - trust in yourself to carry the weight of your real emotions; knowing you're strong enough, and, ultimately, gentle enough to release them and move on.
The phenomenon of girls cutting themselves seems to be directly linked to the repression of anger. http://www.womensenews.org/story/mental-health/040415/girl-talk-why-we-cut-and-burn-ourselves