You are never being 'dramatic' when you vent.

I'm not a psychologist or a therapist, but when it comes to venting about things that are on your mind which make you feel certain emotions, remember that venting about things is just as normal as the emotions you feel. I vent about things a lot, and that's normal. IRL or on the internet, I vent more than I rant.

But venting about things is not you being "dramatic" and shouldn't be compared to being dramatic. The difference between venting and being dramatic is that venting is just something natural that you do in response to the things that really irk you out, and being dramatic is simply a choice. The sad thing that makes venting a "choice" is not doing it, which is true. People don't vent (even in detail) because they think they'll be seen as being dramatic. 

But the truth is that it's not dramatic whatsoever. Just like how you shouldn't contain your negative emotions such as sadness within yourself, you shouldn't sugarcoat how you're really feeling. There's no such thing as naturally being "dramatic" when you vent about something.

Vent about the passing of your pet? That's not being dramatic. Vent about being kicked out of the house you live in from a family altercation? There's no "drama" in venting about that. Vent about how your school or job has treated you like shit? Where would being dramatic even play into that? 

Regardless of what you vent about, you're not being dramatic to any sane person whatsoever. However, not to have the silence-is-violence type of belief, but if you're not being open about the things that you should vent about, then that's just going to translate into the things being perfectly fine and that they don't bother you to an extent.

So when you vent about something, remember that you aren't being dramatic. You're just being open about it, and that's all that matters.