Please help - heart breaking

I just discovered the person I am in love with has a secret email account and signed up for three on-line dating services. I noticed he did it 2 days after we had a big fight and I had left crying, but we had no resolution or closure as to ending. A few weeks later he said he wanted space to figure things out. Am I a total fool? Yes, as I write that I think I answered it. We have had trust issues in the past (4 + years) but to be truthful, there were all my mistakes and he has beat me over the head for them again and again as well as make me feel terrible for the deceit...so is he punishing me now for this? He is actively on-line trying to meet girls while I have been devastated the past three weeks since our fight trying to figure out what happened. Now I understand the behind the back feeling of betrayal - it is the worst pain ever. Or do people in this day and age just feel justified to go on-line and check out options after a fight or break up. It seems very harsh to me. Please advise. I want to go tell him he is a pig (even if no dating has even occured yet), it is the act of signing up while we were still somewhat involved. Has anything like this ever happened to anyone? Please share with me. I don't even get the on-line dating, I have never done. Or should I keep cool and my distance and wait a couple weeks and tell him off (if at all)? I feel bad too that I snooped and found this out about him, but I had a bad feeling and I can't believe it turns out I was right. Thank you in advance, I am really in pain and confused.