Would you have an affair with a much younger very good looking man?

I met someone two days ago whom i have known of for about five years. This person used to play football with my now ex partner. The ex cheated on me and since then I have not found it easy to trust and have lost my faith in whether I will find love again. This person approached me and starting chatting me up. He didn't say he had a girlfriend in fact he said he didn't. We got talking and it was nice and he was very definintely coming on to me. When he was leaving he didn't ask for my number so I offererd it to him. He seemed a little reluctant but took it. I should have known then. The following day he bombarded me with texts and after a while he told me he had a girlfriend but wanted to remain texting - I though it would be harmless so I agreed. Since then the texts have gone on and he wants a physical relationship. I have agreed to meet him but so far we haven't done anything. I do feel its wrong to be with someone who has a partner but he is very attentive and persuasive