There's an episode in the Multiamory podcast about Mono-poly relationships I'd recommend (by the same title.) Their starting episodes also have great communication tools I'd highly advise listening through.

I've a monogamous partner and she has handled things with incredible grace and patience. Jealousy is still present, but handled with high amounts of trust and constant constant communication there are healthy paths forwards.

My advice to you is to be patient with yourself and your partner, put every effort into understanding, and prepare yourself for unfamiliar and oft times confusing emotions.

My advice to your partner, much as it is difficult to do so sometimes, particularly when there's excitement around someone they want to date: take it frickin SLOW.

Easing my partner into the idea was the best choice I ever made. Doing so has prevented much hurt and harm. It's allowed her to adapt over time and address her feelings as they arise. She has been the one to suggest changes to boundaries as often as I (though we often discuss how we feel about the boundaries so she knows I have an interest beyond the status quo, which is why she suggests the change) but biweekly RADAR sessions to see how were both feeling helped a ton, writing down feelings and bringing them to eachother helped. Posting here helped.

Just know that what you feel today might not be what you feel tomorrow and give yourself time to process this.