I need relationship advice! Going through break up.?

Me and my boyfriend, have been dating for three years now and today i found a girls debit card in a duffel bag he uses, i looked her up and she works with him. He says that he just went to buy her cigarettes and she forgot to get the card, which is stupid bc who would forget their card and he wouldn't have had time to do that at work! Well during this he was just quiet and kept saying the same thing over and over when I asked a question. I know he did something because this isn't like him, then he just walked out and said fine don't believe me. After all of that i finally got him to open up and he just started crying and told me that he loved me, bt then said he honestly didn't know if he still did, that he doesn't feel as happy anymore and that we are emotionally detached. I don't feel this way at all and have no idea how i made him feel so unloved. He says my attitude has a lot to do with it, bt i honestly do not give him that much attitude. we get in fights here and there but it's nothing that bad. I broke up with him and he told me he needed a few days to think and try to remember the good we had in our relationship. I need advice on whether he is using this to just avoid the cheating or if he really feels this way. I also need advice on what to say if he says he still wants to be with me. I want to be with him, but I don't want to get cheated on. everybody tells me that I deserve better. I know I do, but I love him and can't help it.