There are several synonyms for the phrase "fuck over" that convey a similar level of betrayal or mistreatment. One common choice is "screw over," which implies a deliberate or intentional act of harming someone for personal gain. Another option is "stab in the back," which suggests a particularly sneaky or underhanded form of betrayal. "Betray" or "double-cross" are also good options, as they clearly express a sense of disloyalty or dishonesty. Ultimately, the choice of synonym will depend on the specific context and tone of the situation, but all of these choices effectively convey a sense of being let down or wronged.