If you've really grown to care about him, then the last thing you can want for him is the pain of a divorce. Step back gracefully and put him out of your mind as a romantic prospect. MAYBE some day he could be, but not right now and probably not for some time, if at all, so why torture yourself and him?
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.