OnWhen I turninged eighteen, I had to get my acts together and, so I started a new life by moving from what was my birthplace, a little village in the countryside, to one of the biggest cities in the country.

Usually, I don't say "on turning"; sometimes, in more formal English, people use "upon," but generally it is not popular. Additionally, act, in the phrase "I had to get my act together" is always singular. Stylistically, what was my birthplace also doesn't make much sense, so just take out what was.

Hitherto, I had just had a settledbecome friends with a group of people with whicho I used to hang out and from whom I learned nowith. To be honest, I didn't rleallyrn constructive social dynamics to say the truth.behaviors from them.

This writing is different from how English speakers talk, it is much more formal and a bit long. Try to break your writing down a bit, and reorder the sentences so they make more sense.

In fact, I can tell that overcoming the several obstacles I faced and not being overshadowed by ruthless people bore weight to the cause.

This might have been a typo: "the" not "te."

So, what can I say, were I to face the situation of having to choose again my path in life again, I would definitely select this very one, for it has opened my eyes.

Again usually goes after the again, so I reordered the sentence as "my path in life again."

OnUpon (or After) turning eighteen, I had to get my acts together and, so I started a new lifechapter by moving from what was my birthplace, a little village in the countryside, to one of the biggest cities in the country.

"A new life" sounds a bit dramatic. Like you are completely starting over (new family, new job, basically everything new). Maybe use "turning over a new leaf" or "starting a new chapter of my life".

Also, the sentence is a bit long. Maybe divide it into two separate sentences.

And to be honest, had I known what it had in store for me, I would have set off even earlier, as this experience, and of course that decision of mine, was pivotal in how I now grapple with the misfortunes I encounter in my path.

Very good. Perhaps a bit long.

Hitherto, I had just hadonly a (settled) group of people with which I used to hang out and from whom I learned not really constructive social dynamics to saytell you the truth.

"To say the truth" sounds stiff and a bit unnatural.
Settled also isn't the best word. I'm not sure what it's supposed to mean here.
"Just" is fine, but "only" sounds a bit more natural.

Not until I left that place, did I discover the outside world and how other people behave.

No comma.

Grievances were not the order of the day; monotonous and wearisome routine was not contemplated.

Very ominous and a bit vague. Not completely sure what you wanted to convey here.

Likewise, although I am not completely sure of how it happened, my self-perception grew strongerbecame better (or "had improved").

Maybe "self-awareness" or "self-esteem" is better than "self-perception". Self-perception means moreso something like what you attribute to yourself, while self-esteem is more emotional and tied to whether you perceive yourself as "good" or "bad" (which I think you were going for).

In fact, I can tell that overcoming the several obstacles I faced and not being overshadowed by ruthless people borecarried weight toin the cause.

The last part is a bit off. Grammatically fine, but not exactly how you would say it in a diary entry / essay.

So, what can I say, w? Were I to face theis situation of having to choose again my path in life again, I would definitely selectchoose this very one, for it has opened my eyes.

I am not in the dark withabout the value of my own person and being rid ofself (my own worth), having freed myself from the sword of Damocles of low self-esteem.

OnWhen I turninged eighteen, I had to get my acts together and started a new life, by moving from what was my birthplace, a little village in the countryside, to one of the biggest cities in the country.

And tTo be honest, had I known what it had in store for me, I would have set off even earlier, as t. This experience, and of course thatmy decision of minethat led to it, was pivotal in how I now grapple with the misfortunes I encounter in my path.

Hitherto, I had just had a settled with a group of people with whichom I used to hang out, and from whom I learned not reallyquite constructive social dynamics, to saytell the truth.

Not until I left that place, did I discover the outside world, and how other people behave.

In fact, I can tell that overcoming the several obstacles I faced, ands well as not being overshadowed by ruthless people, bore weight to the cause.

So, what can I say, w… Were I to face the situation of having to choose again my path in life, I would definitely select this very one, for it has opened my eyes.

I am not longer in the dark withabout the value of my own person, and beingI am now rid of the sword of Damocles ofthat is my low self-esteem.