WordNet sense 1 (be sexually unfaithful to one's partner in marriage):

cheat, wander, cheat on

WordNet sense 2 (deliver to an enemy by treachery):

sell

WordNet sense 3 (disappoint, prove undependable to; abandon, forsake):

fail

WordNet sense 4 (reveal unintentionally):

bewray

WordNet sense 5 (cause someone to believe an untruth):

deceive, lead astray

WordNet sense 6 (give away information about somebody):

denounce, grass, rat, shit, shop, snitch, stag, give away, tell on