I HAVEN’T SLEPT= We use the present perfect tense to talk about a present situation caused by a past action, for instance:
- I have bought a new car = now I have a new car (because I bought it)
When she says "I haven’t slept at all in days" she’s not talking about her sleeping problems, but rather about her present situation: I feel physically very bad (as well as emotionally)
Another use of the present perfect tense is to talk about an action (or a series of repetitions of the same action) that started in the past but continues now in the present:
- He has phoned me every day for three weeks = and he still does
In this case, she’s not talking about how bad she feels because she needs some sleep, she says that her sleepless nights (nights without sleep) continue up to the present. That means that she hasn’t got over the situation, she is still heart-sick (very sad about her love problems).
Both interpretations would be grammatically accurate. Personally, I think the context here favours the second interpretation.

AT ALL= We use this phrase to emphasize negative and interrogative sentences:
- I don’t like her at all
- Are you listening at all?

I HAVE BEEN HERE MANY TIMES= Again, present perfect. The action is repeated up to the present, so now I’m here, but I’ve come here many times before.

WHAT CAN I DO...?= A rhetorical question: she’s not really asking anyone, she’s just expressing her puzzlement, she thinks there’s nothing more she can do about it.

CARE= The spelling AR is usually pronounced like the vowel in CAR, but when it is followed by a written vowel then it is usually pronounced like the diphthong in CHARE:
- car / care /kɑ:/ /keə/
- to mar, Mary /mɑ:*/ /meərɪ/
- far, fare /fɑ:*/ /feə*/
- bar, baring /bɑ:*/ /beərɪŋ/.

TO GET YOU THERE= To make you understand, or to make you feel this the same way as me.

THERE’S ONLY SO MUCH I CAN TAKE= I can only suffer things up to a certain limit, but no more than that.

I JUST GOT TO LET IT GO= I simply have to let it go; I just must let it go.

ACHING= Feeling pain, suffering. Pronounced /eɪkɪŋ/. If you have a pain in your head you have a "headache", if you suffer from love you have "heartache".

IN A FUNNY WAY= In a strange manner. A funny thing may be something that makes you laugh, like a joke, or something very unusual (funny= odd, strange).

CALM= We don’t pronounced the L here. /kɑ:m/

GONNA (conversational English)= Going to.