Masquerade

What a lovely journey from despair and unhappiness to the light and freedom.
When I remember that English is not your first language, I stand back in amazement, as your grasp of it is superb. Some might even say, more comprehensive than many whose mother tongue it is.
Beautifully written.
No crit - except for perhaps on first line had instead of has and then keep the tense in the past. 'Painted a colourful mask' and knew instead of knows etc.
Jx

I just thought you need to unite the tense all through in past simple. Still it's your choice bro.

Once in my life,
when maturity (had) yet to bloom,
I found myself searching
for the perfect identity
(to) wear.

I paint(ed) a colourful mask
to hide my flaws and lackings
but my heart (knew) no peace
for I (knew) I (was) lying.

My soul was trapped,
imprisoned by the shell of self.
I (was) surrounded by people
and yet (I'd) never been more lonely.

Unhappiness,
it was my constant shadow.
Slowly, despair showed its face
when others left me
once (they'd) seen though the mask.

Overcame by weariness,
I (casted) away the lies
and broke the mask into pieces,
only to discover the truth in life.

The perfection that I (sought)
is only a fool's dream
as no humans can be truly perfect.

The moment I (embraced) my true self,
the prison vanished and I am finally free.

Today,
in the absence of hypocrisy,
I am happy.

I think I am. I am trying to edit my piece there, only if I get the time and some help.

It's overcome not [overcame] and cast not [casted]. I like this one, it has a good rhythm to it. A great piece of introspection. Nice! ~ Gee.
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The problem with the English language, is it breaks its own rules on a regular basis
Cast is the same present, past and future tense. I have cast my net, I cast my net, I will cast my net.
Overcome is another verb - over came, overcome, overcoming, so yes you are correct in overcame being the past tense.
However in your phrase 'overcame by weariness' the verb 'was' (past tense of to be) is missing. Written in full it would read I was overcome by weariness. In very basic terms 'was' is your past tense, so overcome is in present tense. Overcame becomes the past participle. It's all to do with conjugation of verbs - a fairly complex subject.
Of course this is made more complicated by the fact you don't actually have to write 'was' to put overcome into the correct form............
Suffice it to say, Gee is correct and it should be overcome.
English is not a straightforward language.

Exits stage left, worrying she has just confused you even more.

Do not give verb tense another thought. Your English is superb.
I was just trying to explain why it was like it is. Sometimes it's wise not to think about the mechanics of something and just do it.
It's a great poem. Jxx