It sounds like you can do one of two things; talk to her and prepare yourself for all the possibilities of what might happen, or suck it up and play mono. What would keep you healthy and happy in life? It its the latter then find all the reading material you can, find a local group, or start one. Invite her to explore poly together before getting into any relationship dynamic. Be educated and really ready, with a solid foundation, before going about finding and attempting another partnership along side of her. You've already started reading here. Maybe start with telling her about this site and then look at the tags in the search engine to see what she might find interesting to read.... good luck.
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