Is getting over the jealousy the main thing? Could anything here help? You do more page 5 things? She does more page 6 things?
I mean... you could try. But if the bottom line is that poly configurations just are not your cup of tea no matter what -- it is what it is.
You stating this...
From the beginning, I did not want to be nonmonogamous, I only did it for her.
...is a big red flag. You are going against your own self/best interests if you do something your are NOT actually willing or eager to do. That is not being honest with yourself or with her.
It is possible to have a paradigm shift and change a core belief -- but not without serious work. So if you are feeling "meh" about polyshipping to start? And just along for the ride because you wanted to be in her orbit?
That's not sounding like you changing a core belief hard limit thing like "I am monoamorous but this is the exception to the rule" is happening. Could it be? Could take your inner temperature on that to see if it is still "meh" or what. But LISTEN to yourself this time honestly when you ask THAT question of yourself:
I am monoamorously wired. Is this polyship with her the exception to the rule? Am I willing to put in the work required AND give up some of my wants like "my partner is exclusive to me?" Can I offer her me as an agreeable, healthy companion under these conditions?
Hang in there. I know this does not feel fun.