My fFavorite pPersion

English title capitalization rules

I wanna share that my favorite person is not someone that is in my blood, but a girl that an couple years ago showed up in my life a couple years ago and change everything.

The sentence structure is unnatural here

Today she has become my wife, the person that has all my heart, the one that I'lld give everything to make her happy.

1. You should add “has” after “she” because she is your wife now
2. Since you’re talking about something hypothetical, you need to use the conditional tense, so this changes “I’ll” to “I’d”
3. The last bit is a bit of a complicated phrase in English, but when we say a phrase like this, we don’t add the pronoun at the end

I could write thousands of lines, but that still wouldn't be enough to express how much I love her, but anyway...

This sentence is fine and understandable, but it feels like you could add some things to make it sound better. What I added is entirely optional.
Additionally, the word “lines” works, but is used less commonly than words like “sentences” or “words”

My favorite persinon.

I wanna share that my favorite person is not someone that is in my bloodfrom my family, but a girl that an couple years ago showed up in my life and change everything.

Today she becoame my wife, thea person that has all my heart, the a persone that I'll would give everything to to make her happy.

I could write thousands of linewords, but that wouldn't be enough, but anyway...

That's my favorite person in the whole world.