My partner cheated while I was sick

I (27F) just found out my boyfriend (30M) cheated on me while I was recovering from surgery. We’ve been together for four years and I never suspected anything like this. He says it was a mistake, but I’m struggling to process my feelings and decide what to do next. Should I stay and work it out, or move on? Any advice? #SurvivorSupport #RelationshipAdvice #TrustIssues