I really don't understand this?

Question:

"僕の歌を聴いては泣く, 君はどこにいったんだろう" or "Kimi no uta wo kiite wa naku, kimi wa doko ni ittandarou" translates as "Listening to my songs, rather than where you will once"
Which is really different if the comma in the middle is taken out. And if replaced the comma with a period, the meaning changes again.

I just became aware that in translating, normally people would rephrase the basic meaning in Japanese to something that would be understandable for average English readers.
But I can't even get a grasp of what it means in this phrase because it keeps changing every time a punctuation mark differs. So confused. ;_;

This problem's really killing me on the inside, but I love translations. Can anybody clarify the phrase above? And also, does anybody have any tips on translating from Japanese to English?

Answer:

"You used to cry over my songs, now you don't even care anymore..."

Literally,
"Wondering where has the part of you gone, that used to cry every time you listen to my songs?"

I think all you need is to try even harder in understanding Japanese. You may want to have a native checker friend, who is trained for translation if you can. Japanese is not an easy language...
Good luck :)