naw, rust doesnt want marty's wife....he was talking about his ex and their kid...it also goes with the whole acceptance thing he has...everyone on the outside looking in at him thinks his life is all fukked up and needs 'fixin'....but in actuality, it's not and he's perfectly fine with his life and who he is as a person...but since it doesnt fit the perception of what people think, that's why they act like something's wrong with it...ex: the man doesnt want a woman in his life and he's fine with that, but everyone thinks he should have a woman and family...he had that and that aint the shyt he wants anymore...
another thing about that phone call scene: rust covered marty's ass about the cheating shyt...i think marty finds out and that's why him and rust stayed partners for so long...also, it's part of why marty still holds rust in such high regard...i think he admires the fact that rust accepts who he is, lives his life the way he wants, and doesnt give a fukk what people think...he doesnt try to be what is acceptable to society; doesnt put up a front; he's not conflicted....all the opposite shyt that marty is...it's one of those 'i dig what you doing and i might agree, but i aint gonna do it' kinda things....