I realize your marriage isn't working out how YOU planned it, but it takes two to tango and yes, you have and are cheating as far as I am concerned.
If you really aren't happy and he really isn't willing to do the work to reconnect with you then I think you both need to find good therapists to work on getting through the pain you have caused by taking this path way back when you were not getting your needs met and decided to take the road of deciet rather than integrity. I suggest you also find a good lawyer and that he does too and work on your separation. There is no good reason to stay it seems and I'm sorry, finances are not a good enough reason just as kids aren't. It may take time, but it is possible.
I'm really quite dismayed that a poly guy would be interested in engaging with a cheating woman. Not very poly and a tad opportunist. What's he thinking!
You've got some work to do it seems to make this right. Lots to talk about with your husband. You broke trust with him sex or no sex. Intimacy or no intimacy. Just because your marriage wasn't going to your plan doesn't give you the right to become selfish. Rather it was time to get to the bottom of it and not be complacent. You missed the boat to sorting it out in both your best interest really. So get to work and do it now would be my suggestion.
Now, I realize this post will be uncomfortable and not be what you want to hear and for that I apoligize. From the info given and from my experience, its my opinion and you can take it or leave it. Your choice