cheating

i was with friends one night and my ex came over around 12:00pm , i was dating this guy shawn but we got in an argument and later on i broke up with him then turned off my phone around 2:00am. after that me and my ex fooled around until like 5:00am , and he left. i fell asleep , woke up around 7:30am and shawn saw the message around 8:30am , alot of people are saying i cheated on him but in my defence when i did stuff with my ex i was thinking I was single. whats your guys thoughts ?