Economically, Africa suffered because able-bodied males were most prized as slaves. Without them, there were very significantly fewer to work on the homeland. Sadly, powerful African traders who could have been importing and exporting effectively responded to the European desire for black labour.
Yes, it was Africans who sold their own compatriots in dire circumstances. Slavery brought a severe social divide between white and black people, an ill that soured relationships and has still not been eradicated completely.