11:16 AM PT -- Melissa has responded to Tamar, telling TMZ ... she stands by her story that Vincent verbally and emotionally abused her while recording her first Dream album at age 14, and that he asked her to lose weight. She says she is not attempting to insert herself into Tamar and Vince's family matters ... and just wants to shed light on a big problem in the music biz.

Tamar Braxton is slamming a member of the girl group Dream who claimed Tamar's estranged husband abused her ... Tamar thinks she's a "thirst bucket" who is just out for attention.

Tamar set her sights on Melissa Schuman, who said Saturday Vincent Herbert verbally and emotionally abused her when she was 14, while recording for Dream. She says Herbert, who was an associate executive producer on the album, also forced her to lose weight.

Tamar says Vincent's criticism is all part of "artist development," noting Melissa had no complaints when Dream was selling millions of records. Tamar warns, "Don't EVEN TRY to use our personal Family situation for attention!! All the greats had to do it, GAGA, Toni, myself ... All had what was ARTIST DEVELOPMENT!!"

Tamar says, "OK ... now here is what you WON'T be doiong thirst bucket!! I know u saw damn puffy MTB ... the industry THEN was like bootcamp for ALL of us!"

FYI ... Melissa also accused Nick Carter of raping her in 2002 ... Nick says their encounter was mutual.