Is it true that the veil is lifted between Allaah and His slaves at the time of breaking the fast?

This hadeeth is not part of the Prophet’s Sunnah, and it is not something that is known to the scholars and muhaddithoon in their books and Musnads. It is not narrated
except in a few books whose authors filled them with fabricated reports,
false reports, stories and myths, such as Nuzhat al-Majaalis wa Muntakhab
al-Nafaa’is, by the historian and man of letters ‘Abd al-Rahmaan ibn
‘Abd al-Salaam al-Safoori (d. 894 AH) – pp. 182-183, Chapter on the virtue
of Ramadaan and encouragement to do good deeds therein. It also appears in
the tafseer Rooh al-Bayaan (8/112) by Ismaa’eel Haqqi al-Hanafi
al-Khalooti (d. 1127 AH). They mentioned a hadeeth similar to that referred
to by the questioner, in which it says: “Moosa (peace be upon him) said: ‘O
Lord, You have honoured me by speaking to me directly. Will You give anyone
else something like this?’ And Allaah revealed: ‘O Moosa, I have slaves whom
I will bring forth at the end of time, and I will honour them with the month
of Ramadaan, and I will closer to one of them than to you, because you have
spoken to Me when there are seventy thousand veils between Me and you, but
when the ummah of Muhammad (peace and blessings of Allaah be upon him)
fasts until their lips turn white and their faces turn yellow, I will lift
the veil between Me and them at the time they break their fast. O Moosa,
glad tidings to the one whose liver thirsts and whose stomach hungers in
Ramadaan.” 

Moreover, in the matn (text) of this hadeeth there is something which indicates that it is munkar (i.e., unsound), which is the words “I will be closer to one of them than
you” – referring to Moosa (peace be upon him). It is well known in Muslim
belief that the Messengers and Prophets are better than all other humans,
and Moosa is one of the Messengers of strong will, so how can Allaah be
closer to His slaves than to His Prophet Moosa (peace be upon him), of whom
He said (interpretation of the meaning): “And We called him from the
right side of the Mount, and made him draw near to Us for a talk with him”
[Maryam 19:52]? And Ibn ‘Abbaas (may Allaah be pleased with him) said:
He drew so close that he heard the scratching of the Pen – i.e., writing the
Tawraat (Torah). See: Tafseer al-Qur’aan il-‘Azeem by al-Haafiz Ibn
Katheer (5/237). 

To sum up: The hadeeth mentioned is not in any of the reliable books, so it is not permissible to attribute it the Messenger of Allaah (peace and blessings of Allaah be
upon him) or to believe what it says. 

And Allaah knows best.