Yes all comments are super helpful. I'm not doing the standard forum, ask for one hard and straight answer and then ignore it completely. A collection of thoughts from those more experienced than I for me to mull over and fit into my personal situation is all I'm really looking for. And calling me out on things goes completely along with that.
I can certainly see what you mean by the wrong use of accidental. I really just meant that I didn't go looking for it it just happened. However, I let it and I'm actually ok with that. I will take full ownership of that. I saw where it was going and let it go there and I have no regrets about it.
The problem is how do I balance trust with my husband's feelings. Especially since so long as I am careful with time management he will trust me completely regardless of whether that is deserved. He isn't as openminded about socially non-conforming situations as I am. If he had a similar personality and beliefset to me I'd certainly tell him. I'm not sure at the moment he can grasp the idea of having multiple partners in this way. I think he could in the future though given some time to be introduced to it more fully at a very slow pace. There is actually a huge part of me that wonders if I only want to tell him to assuage my own guilt. People do that cheating situations and one night stands all the time, and both of us have agreed that such things are stupid and meant more to make the guilty party feel better than for reasons of true honesty. I'm not sure if my situation is any different. Except I suppose that it is ongoing and long term.
Thank you for the correction in terminology, I'd seen that somewhere, but wasn't sure if it applied since my husband and friend are not at all involved with each other and the V notation seemed to apply that all three parties were involved with each other a bit, it seems I was perhaps misunderstanding the V notation.