relationship advice

My boyfriend and I have been together two years and are planning on buying a place together. Our first year of our relationship he had two friends who strongly disliked me because they thought he didn't talk to them as much. I never stopped him anyways they texted him one night saying he said he wanted to cheat on me. Blah blah this was a year ago. So last night I went out with a old friend I haven't seen for about s year and she told me she had to tell me so
Something. My boyfriend is friends with hers that's how we met. She told me her bf told her my boyfriend said he would cheat on me to him Aswell. They didn't talk for about eight months before yesterday so if he said this it would be a year ago. My bf is completely denying it. And he seems sincere. But I can't trlll. I don't want to be that idiot dating someone who'd say that. Opinions plz