Cheating or not cheating ?? 🧐

So me and ex boyfriend had broken up in October and haven’t been together since but we would still have sexual intercourse ..so a little later I met this guy at work and he’s so cute and we text and talk and he invited me over a few times so I went and we eventually had sexual intercourse and we just text and talk regularly now and sometimes he still wants me over but now my ex boyfriend is thinking about getting back in a relationship ..should i tell him or not ? I don’t know what to do someone help !!and another problem I’m actually feeling them both 😭