So im trying to understand this condition so i can get rid of it... Im wondering now did i get this because i was constipated all the time or i was constipated becuz my muscles down there are abnormally tight?

Your stools would be thin if you were abnormally tight. I suffered from thin stools for around a year before I acquired my fissure.

Well that settles it then. I should have gone to a rectal dr not the stupid gi doctor that couldnt figure out what was wrong cuz she didnt see anything. Well when she gave me the colonoscopy she finally found it but i bet you a crs would have known my symptoms and given me the right meds, like tbe nitro ect before i tore my ass open. The gi doctor thought i had polyps. Grrr im in so much pain today...

And how does fiber help? Wouldnt a stool softener be better to just make everything soft and passable?

The key is not to have big, hard stool. I've been drinking fiber drinks for the past two weeks now. Stool is softer (but shouldn't be too soft as that's hard to get out).
I used to just eat Oat Meal in the morning. That along makes my stool soft.
And yes, I made the same mistake as yours. The GI doctor wanted to stick a camera in to check out. I told him I thought it was an internal hem but then he said it's actually a fissure. He prescribed me cortison ugh!!
Didn't even know about nitro cream and dili cream until I came here.
I think warm sitz baths really help. Do 15-min when you wake up and 15-min before you sleep. Twice a day.
Make sure you have normal stool.. which means NO SPICY FOOD.. cut down on a lot of caffeine and eat food that has less chance to give you bad stomach. Yes, this means a Strict Diet Change. To me, it's a whole Lifestyle change. I've been ignoring my fissure for years.. didn't know what it was. I am gay and I do anal sex.. and I thought that was just part of the "pain".
I've been using coconut oil (organic, virgin) outside my anus. It provides lubrication and it slows/stops itching which I had.