GAS (AmE) = petrol (BrE), fuel. Short for "gasoline".

IN THE RED = with an alarmingly low amount (of money or, in this case, fuel, psychological sanity). The metaphor comes from bank accounts. When you don't have money but debts, that amount is marked in red figures, so "to be in the red" is when you don't have enough of it.

NOTHING = Spelled with O but pronounced /nʌθɪŋ/

ON MY HEAD= If something is on your head, you feel the moral responsibility for it, so maybe she’s here referring to all the guilt she feels about her bad life, and that’s what is driving her crazy, because she can’t take any more (after all, this song appeared in the remake of "good girls gone bad"). We can say the phrase "on your head be it" to tell someone that they will have to suffer the consequences of their wrong action or decision.

WANNA= Want to

INSANE= crazy, mad.

IT’S A THIEF IN THE NIGHT= This biblical sentence refers to someone or something that appears unexpectedly to steal something from you. In the Bible it refers to Jesus, who in the last days will return like "a thief in the night" to try and "steal" (take away) the souls of good people from the hands of Evil (2nd Peter 3:10). But in this song, whichever or whoever is coming like a thief in the night has no good intentions at all, it’s not going to save her from hell, but to send her straight into it.

GRAB= Take

CREEP= Move slowly and soundlessly (with no sound), like insects do. We also use the word "creepy" to mean "scary, spooky, fearful", so this word, in this context, is talking about movement but also bringing to us a sense of pure fear.

CONSUME= The U in this word is pronounced like "you" in BrE but like "oo" in AmE. She says "consoom". BrE /kɒnsju:m/, AmE /kɒnsu:m/.

DISEASE= Illness, sickness. If you have a disease you are ill.

IT’S TOO CLOSE FOR COMFORT= You would feel more comfortable if it were a long way from you, but it’s very close and you are not comfortable (it’s coming to get you and you know it). The word COMFORT is spelled with O but pronounced with the vowel in HUT (not the vowel in SOCK).

BRAKE= To press the brake pedal in your car to make the car stop or slow down.

PUT ON YOUR BRAKE LIGHTS= Slow down or stop (because you’re moving fast in the wrong direction). If you brake your car, the brake lights go on, so if you put on your brake lights, you’re braking. In this line she’s talking to herself. That means that if she’s heading to madness, it’s her fault, it’s something she’s doing rather that something which is happening to her.

THE CITY OF WONDER= A place full of marvellous things (wonders), a wonderful place. By now we now that those wonders are illusions, bad things that look or feel good, so they attract you in the same way as ancient Greek sirens, with her beautiful bodies and songs, attracted sailors to the cliffs to kill them and eat them.

AIN’T GON PLAY NICE= It’s not going to turn out nicely, it’s going to be horrible (if you don’t stop).

WATCH OUT= Be careful.

YOU MIGHT GO UNDER= You will perhaps sink. To go under is to go under water or as if under water.

BETTER= You had better = you should.

YOUR TRAIN OF THOUGHT= Your capacity of reasoning, your rational mind. But usually, when we say "my train of thought" we refer to a single threat of reasoning, a developing idea, for example, we’re talking about politics, explaining why something is wrong, something disturbs us and we say "sorry, I lost my train of thought" (I don’t know what my next step of reasoning was going to be).

ALTERED= Changed

FALTER= To hesitate (doubt) in purpose or action, as from loss of courage or confidence.

IT’S LIKE THE DARKNESS IS LIGHT= It is or feels as if the darkness is not darkness, but light. This means that bad thinks look good, but they aren’t. When your mind is disturbed, you can’t see reality clearly, so you can’t tell right from wrong.

AM I SCARING YOU= Are you afraid of me?

AIN’T USED TO= I’m not used to. AIN’T is the colloquial negative of the verbs "to be" or "to have", especially in the USA.
- I ain’t got no money = I haven’t got any money
- He ain’t no doctor = he’s not a doctor

FADED= If something is faded it has lost intensity, in this case, colour.

IT’S LIKE THEY TALKIN’ TO ME= I feel like the pictures are talking to me.

DISCONNECTIN’ ON CALLS= When I phone you, your telephone disconnects, so I can’t speak to you.

YOUR PHONE DON’T EVEN RING= It should be "doesn’t", but in colloquial English we sometimes use "don’t" for the 3rd person too, and we can also use no –S (e.g. "he go to school), but that’s even more unusual.

I GOTTA GET OUT= I have to get out, I’ve got to get out.

FIGURE something OUT= Try to solve a problem, find the exit to a troubling situation. The original song uses a rude word here, but on the video that part has been erased so you can’t hear it.

RELEASE ME= Liberate me.

CURSE= Malediction, an evil spell, something terrible.

RELEASE ME FROM THIS CURSE I’M IN= I’m in a horrible situation, so please, take me away from here.

TRYING TO MAINTAIN= Trying to survive, trying not to "sink", to stay sane.

STRUGGLING= Fighting (to solve this situation); making big efforts.

IF YOU CAN’T GO, I THINK I’M GONNA AH, AH, AH= If you (the disturbing thing) don’t disappear from my life, I’m going to go crazy or die or simply explode.