Sleeping with a colleague.

I slept with a colleague and now I rejected him his treating me horribly at work. I really want to quit my job because I feel so uncomfortable. What should I do? His basically my manger at work and he tells me what to do and gives me all the work. I really can’t stand being around him especially since I’ve rekindled things with my ex and he found out about the colleague. I don’t know what to say to my boss or what to do. The only reason I wanna leave is cause of the colleague.