TMZ spoke with Terry Avery -- who says he was married to Nia from 2003 - 2014 -- and they have a 13 year-old daughter together ... which is why he's letting Chris know he means business.
Terry says he and Nia were separated when she got knocked up ... but since Avery knew it wasn't his kid, he finally filed for divorce. He claims he had no idea the baby belonged to C.B.
Avery tells us he's aware of Chris' notorious temper and says he better not lose it around Nia and the kids, or there will be repercussions. He was not more specific about what that means, but its clearly a threat.