Betrayal in a marriage,is this one or not?

A couple months ago my husband and I had gotten into an argument, he went out and was sending rude texts and kept calling,in one of the phone calls he said "well I'm going to go cheat on you tonight!",me not knowing what to say but wanting to hurt him said I'd do the same thing (which I didn't and would never). Anyways,he didn't come home til 7 that morning, I asked him where he was and who he was with,he said he went straight to his parents then came home in the morning. Few days later I found out he was at another womans house,he admitted to that,then hours after that another person told me that my husband was actually in this womans bedroom with her alone til about four thirty in the morning. He tried to deny it but then admitted to that also. I asked him what happened he said " i was going to cheat on you, I had every intention of doing so,but the only reason I didn't was because I couldn't get an erection cause I was thinking about you and didn't want to hurt you". He thinks he did nothing to betray me. But I feel very hurt still. We are currently seperating. How would you react in that situation? Not sure if I'm to forgive him for something that almost happened but didn't?