I'm sorry you are hurting.
You could take the personalities out of the equation to see if you feel the same when there are no names. Here's how it would read if you remove the names:
At this point I am at a cross roads. I am in a non-poly relationship. The thought of not being in a poly relationship makes me sick to my stomach. (yes/no?)
My desire to be in poly relationship is worth pursuing. (yes/no?)
My options are
1) pursue a poly relationship If I break my non-poly relationship and state my desire to be in a poly relationship, then I will no longer have my non-poly relationship.
2) just suppress the feelings, stay in a non-poly arrangement and hope I can get over not being in a poly relationship.
3) Something else that I can't think of yet or am not aware of yet.
If don't break my non-poly relationship, I risk not having a poly relationship.
Is there any advice on how I can handle this situation? Do I pursue my desire for poly relationship? Do I ignore it and hope I can keep the desire buried without it hurting myself doing so?
When phrased like that, do you still feel as strongly? Would you still feel as strongly about ending your non-poly partnership to free you up for POTENTIAL future polyshipping? If you choose YOURSELF (versus choosing wife or choosing GF) -- where does that put you at? Because who is to say you will stay with Kim if you leave Sarah for her? Maybe you end up with zero partners. Maybe you end up with two other poly partners entirely that are neither Kim or Sarah.
You have to reconcile your desires and make a call there. Is 1a the only open model your wife will consider? Are you clear about what open model relationship you want?
Maybe that could be a helpful talking tool with wife? Or anything here?