R kelly not accepting his trandsgender daughter/son's decision

R. Kelly can't accept the fact he has a transgender child -- a daughter who chooses to live as a male -- and at least one very close relative is attacking the singer as heartless.

Andrea Kelly says R still refers to 14-year-old Jaya as his daughter ... even though Jaya came out as transgender earlier this month and now calls himself Jay.  She tells TMZ, "That's like calling him [R. Kelly] a background singer, not the king of R&B."

The "Bump N' Grind" singer made his feelings clear last weekend ... when a Chicago radio host dared to ask about Jay.  It's apparent, Kelly not only can't handle it ... he doesn't believe it.

Andrea says Jay has not had gender reassignment surgery, but Andrea says she's respecting the change.  Well, that makes one.