Frenemy

"Frenemy" (less commonly spelled "frienemy") is an oxymoron and a portmanteau of "friend" and "enemy" that can refer to either an enemy pretending to be a friend or someone who really is a friend but also a rival. The term is used to describe personal, geopolitical, and commercial relationships both among individuals and groups or institutions. The word has appeared in print as early as 1953.