Thanks for all the advice. I think you are right GalaGirl. I really appreciate you breaking it down for me. I was fearful of how badly she treated me the first time I asked to slow down so I was tying to avoid putting back on me but I now see that if I can weather the storm, this is probably the best course.
I am really wanting to get hew away from "R" now because I have found out that she has told him the level of discord and pain him making himself available to her is causing and he basically said "I'll always be here for you - you are the one I care about". He is toxic to my relationship and is not poly. He just wants to insert himself (no pun intended) as an affair partner, not as my metamore.
Thanks again to everyone here for the support and helping me get some perspective.