Wow, that's a lot. I'm sorry you hurt.
I agree with WhatHappened. If this all began with her lying about an cheating affair? That's not a solid foundation to build a polyship on. Polyshipping is not the "whitewash" for cheating, lying and breaking agreements.
What would prevent her from cheating/lying in a polyship in future?
I don't know if reading this could help or not in your emotional management at this time:
But before you can deal with resolving jealousy, TRUST has to be rebuilt and regained.
My carrot in this situation is that she would allow me to also pursue the same and I am tempted, but I have no idea where to start.
If getting to date -- that is your ONLY carrot to try polyshipping? You know you could have that as a single man too, right? Single men can date.
If her polyship offer to you is incomplete, less than yummy or healthy sounding, does not meet your own needs? You have ever right to say "No, thank you. I am not willing to participate in that."
She's not described what open model
she's proposing. She's not offering you anything well mapped out or inviting you to help map it out so your needs are met. I wonder if she's offering this mostly so she doesn't have
to choose, doesn't have to take emotional responsibility, is looking to assuage her guilt, or misses kid and the cushy you provide at home (because letting a single room is not the same)...
It is good you are thinking or trying to about your OWN long term well being. Rather than just RUSH right into polyshipping with her and her cheating partner so as "not to lose her." This is my response
to a different thread, but it applies here too. You have EVERY right to consider the offer presented to you and determine if it is yummy and healthy sounding for you. And the right to say NO if it is an offer that is not healthy or good for you.
To me it seems you could take a time out. Do nothing yet but allow yourself time to cool off. Then decide what the issues are, what the goals to resolve the issues are, and what the strategy to achieve those goals could be. That's where a counselor can come in and help you. Could go see one on your own to help you sort.
But the #1 thing at this time, and later when you are ready to deal with your marriage goals? To continue it in a new polyship shape or to disband the marriage...
That #1 is taking care of daughter appropriately all the way through. Dependents and their needs trump adults and their wants. To me anyway.
Hang in there.