Follow my heart or listen to what my mind is telling me...

I recently found out that my boyfriend was cheating on me... one minute I want to be with him and try and work it out and the next I don't think I should. My heart is telling me to stay but my mind is telling me to leave. Idk what to do. He begged to me and cried to me asking me to stay with him and that he'd never do it again. This is the first time he's even done anything to hurt me. What do I do I can't deal with this constant back and forth feeling.