Emotions aren't a fluid. They're not going to burst Cinder's metaphorical bottle. Venting and feeling good about it just reinforces having and expressing those negative feelings. Learning to keep your emotions under control is both going to be ultimately better for your own well-being and crucial for being part of a decent society.
Keep it up Cinder, you're doing good.
Bottling up emotion and keeping them under control are two totally different things, though. Take this from someone who's made that exact same mistake and is currently on wonderful antidepressants to
fix said mistake. Emotions aren't a fluid, but if you do just bottle them up they absolutely do get too much to handle.
Keeping emotion under control is, resisting the impulsive actions that result from emotion but
still deal with the issues. Whether its jerky coworkers, condescending bosses, bullying, sexual harassment, you absolutely must fix the issue. Yes, those are all personal examples. Yes, I reacted badly to most of them. Fixing it may mean talking it out, it may mean seeing a shrink, it means whatever helps get rid of the problem in a healthy manner.
Bottling it up is when you simply push the emotions down and don't let them show. I'm seriously resisting the urge to quote Frozen here, but they were seriously right on the money - hiding emotion is baaaaad. Internalising everything ends with problems just going around and around in your head. For me, I did it for so long that I'd just kick everything inwards. Little thoughts would just sit inside and fester, going around and around until they became way too big and it ended with me punching someone anyway.
Look, sometimes you've gotta vent. And venting
does help, if you do it to the right person.
Perspective changes absolutely everything, trust me. I've had problems that built up in my head because I just bottled everything up - and when my girlfriend
did finally drag it out of me, she helped me put everything into focus. It's not about reinforcing negative feelings, it's about getting them out of your system and putting yourself back into the right frame of mind to actually look at them clearly.