American black English differs from standard English in many respects, and tends to be much more colloquial. In this song, they use standard colloquial English, but there is something very "black" about this song: they don't pronounce the sound /r/ just in the same way as BrE does (the letter R is silent except when followed by a vowel).

HOW I'M SUPPOSED TO BREATHE WITH NO AIR= if you ask "how am I supposed to do X?", you don't know how to do it and you think it's not possible, so you're asking for instructions but thinking there is no answer. In the song, there is no inversion in this sentence because it's not a direct question, but a statement:
- direct question: How am I supposed to breathe?
- statement: Tell me how I am supposed to breathe. (=indirect question)
Some languages make an inversion in both cases. The simple rule in English is: if there is a question mark ("?") there is an inversion (and only one). No question mark, no inversion.

IF I SHOULD DIE= We can use the auxiliary SHOULD in an if-clause (a sentence after the conjunction IF) to express that we are talking about something improbable:
- if you see my sister, tell her to come here (maybe you will see my sister)
- if you should see my sister, tell her to come here (I don’t think you’ll see my sister, but if you do, tell her to come)
We can express the same idea saying "if you happen to see my sister, tell her to come here".

CAUSE= because

YOU TOOK MY BREATH AWAY= this is a pun (it plays with two different meanings); the expression "you take my breath away" means "I like you so much" (so much that when I see you I stop breathing out of shock). But in this song, this expression also has the literal meaning: if you take my breath away, I stop breathing, so I may die. She stopped breathing because she left his lover and now she realizes that his love was for her like the air she breathes: if he’s not with her, she can’t breathe any more, because he is her air (the most important thing to live).

LIVIN’= living

DIN'T= (informal) didn't. It is pronounced like "din".

WANNA= want to

DIN’T WANNA LEAVE= The subject "I" is missing (is not here). This happens sometimes in colloquial English (only in some situations where the subject is easily guessed). When the subject is missing, it is usually "I", unless the context clearly indicates otherwise.

MY HEART WON'T MOVE= We often use "won't" (will not) with the meaning of "refuse":
- she won't come= she refuses to come (she doesn't want to come)
We also use it with inanimate objects meaning something like "it's impossible to make it happen"
- the door won't open= I've tried and tried, but it's impossible to open the door

WISH THERE WAS A WAY= again, the subject "I" is missing (= I wish there was a way). The verb WISH is used to express a desire, and is followed by the past tense:
- I wish you were here (I desire you to be here)
- I wish it stopped raining (I want the rain to stop)
- he wished they had told him (he wanted them to have told him)
In this sentence A WAY means "a manner". "Wish there was a way" means "I wish it was possible"

REVOLVE= (a formal word) to spin, to turn around

MY WORLD REVOLVES AROUND YOU= you are the most important thing for me

HARD= difficult

BREATHE= /bri:ð/ notice the different spelling and pronunciation of the noun and the verb. The verb TO BREATHE  is spelled with an ending –E and pronounced with the vowel in TEA, the last consonant (TH) the same as in THE. But the noun, BREATH /breθ/, is pronounced with the vowel in BELL and the last consonant (TH) is sounded as in THING.

WITH NO AIR= without any air. NO is a negative article used with countable plurals and uncountables (the same as SOME but negative). We can use a negative sentence with ANY or a positive sentence with NO:
- I haven’t got any children = I have no children
- She doesn’t need any money = She needs no money
The negative article NO is also used with countable singular, but then it is considered incorrect or slang (very colloquial):
- I need no doctor = I don’t need a doctor

WHENEVER= every time, no matter when. You can also use the suffix –EVER with the other interrogative words meaning "no matter x", e.g:
- whoever you see, tell me = no matter who you see, tell me (every time you see somebody, tell me)
- you can take whatever you need = you can take anything you need, no matter what it is

AIN’T= colloquial negative form of the verb "to be" or "to have".
- You ain’t here = you aren’t here
- I ain’t got no money = I haven’t got any money

GOT ME OUT HERE= again, the subject is missing. Our first guess would be that the subject is "I", but in this case it is very improbable because it is "got me", and the context makes it clear that the subject is YOU.
- Got me out here= "you’ve got me out here". It means "I’m out here because of you". The idea of "being out" means "I’m unprotected, with no shelter (refuge)", so I'm in danger.

IN THE WATER SO DEEP= (you’ve got me) in very deep waters. In English, WATER is used in some expressions meaning trouble, danger (if you are in the water you may drown and die). If the water is very deep, you can’t stand, and you may die, so this sentence means "I am in big big trouble/danger because I don't have you".

YOU GON BREATHE= you're going to breathe. The form "gonna" is commonly used in informal conversational English for "going to" (I'm gonna do it = I'm going to do it), but some people go one step further and make it even shorter: GON (sometimes spelled "gone").

I FLEW RIGHT OFF THE GROUND= the word RIGHT is often used to emphasize expressions of place and time (meaning "exactly"). "I flew off the ground" is redundant, because if you fly, you do it off the ground (OFF expresses the idea of separation).

TO HOLD ME DOWN= to keep me on the ground (to stop me floating)

FOR REAL= if something happens for real, it happens seriously, and is not pretended or imagined (= seriously, truly)

SOMEHOW= you use this word to express that you don’t know the reason for something or how something happens, but it happens