I am in a similar situation...my husband wants me to consider a poly relationship. The difference is that he has been having an affair with the other women and since I found out it hasn't stopped.
He seems to have latched on to Poly as a label for how he feels and wants me to comply so he can move his gf in. All this has devastated me and just fills me with overwhelming sadness, I just don't know who I am anymore. I just keep functioning because of our sons, but even they catch me crying and I can't tell them what is going on because it would destroy them.
All I can say to you is stay strong to your values and don't loose yourself in trying to consider if you could handle this kind of relationship.