Is there ever a suitable reason for infidelity in a relationship?

I think it is easier for us to lie to ourselves than face consequences. I had my husband's ok to talk to guys online. He knew well everything I was doing, then all of the sudden everything changed and I am a lying slut and whore because of it. I know no situation is black and white and im not trying to excuse anyone or myself. But just because I don't see my actions the same way, it doesn't mean I cant understand how much I hurt him.