I feel like an asshole

I needed time for myself because I was dealing badly with depression and I told my boyfriend that and he gave me space for a few days, it was an understanding. We didn't breakup and it wasn't even a break. It was mutual because I did the same thing when he was battling his depression a months ago. But anyway, I was sorting through my emotions and thoughts but still kept him up with news and stuff. I knew he had gone out to a concert for new years, he told me. He told me he got wasted at the bar and that's it but today he just told me that he not only got wasted but went back to this long time friends house and they almost had sex (starting not to believe it). He said they kissed and got heated but he said no because he still had feelings for me. He said that they got lost in the moment because they "both lost someone they loved" because she had just gotten divorced from her husband and I was dealing with depression. I never told him we were breaking up, remember?

He kept using me and being drunk as a valid excuse for what he did. Well, I told him to cut her off out of respect for our relationship. I don't know why he thought that saying "we're still friends, we agreed it was a mistake" was a good idea. He told me last night that he "had no sex drive" but he almost fucked this woman a couple nights ago and wouldn't have told me about it had I asked what happened when he said "I won't tell you what happened and you don't have to tell me what happened" when I was sorting myself out. He says he didn't cheat because he was cheated on before and would never do it. I feel like an asshole and feel guilty for even being upset over this and for making this out to be an issue... Do I even have a right to be upset? I'm disgusted, I really am. What do I do? Are my feelings valid?