polyamorus and trust, I really hurt my husband

I met my husband while I was still married (though seperated) and that caused some issues in the beginning of our relationship. I always though his pillow talk of sleeping with other people was just that, until it wasn't. I was completely against the idea at first for many many years. After a while I started thinking that this was something that he needed. He'd bring it up in the bedroom more often than not. And finally he started logically explaining it to me, why he wanted to sleep with other people, and actually wanted me to as well. He wanted us to do these things together. We attempted it once, with another man, and every thing went great, until it didn't, I don't remember most of it. I was incredibly intoxicated. So we decided to try just chatting with people on the internet. That was going ok too.... until it didn't. I crossed a line I didn't even know was there.I talked about personal life, vagely, and sent a message when we were at a going away party. The message that was sent back my husband read before I did, and it really upset him, it was a simple 'glad you're thinking of me'. Once I realized that this person thought there was more to our interactions than it actually was, I deleted my entire account that I had been using. That's not what I want. From my prespective I was being friendly and flirty, but it wasn't seen that way. and I can understand that. I had a hard time getting into all of this to begin with, and now I'm sitting here, my husband won't talk to me, I have no family connections that really matter, my parents both passed away years ago, we have four children, and I think that I just made the one person on earth, other than my kids, that has unconditional love for me, resent me, I hurt him, unknowingly, by doing that I thought he wanted me to do. I'm completely lost. I didn't want this in the first place, but I feel like its my own stupid fault for giving in and trying, and then getting into it and enjoying it. I don't know how to fix it. After so much loss, I'm not sure I can mentally take another one. I'm scared I'll loose him, and I'm scared that my kids will lose the loving environment that we have made for them.