I'm not in your situation, but just wanted to welcome you and encourage you to continue sharing and reading this forum. There are a lot of people here with good advice and willing to share their own thoughts and feelings. For me, the main philosphy which is underlying the polyamorous lifestyle is the realization that a person can be in love with more than one person and the love they have for a second person does not diminish the love they have for the first person....in fact, it seems to enhance the love for the first person. A very interesting thing happens in polyamorous relationships and when you experience it, you will know it. It's the opposite of jealousy.....it's called compersion.....and it's when you look at your lover and feel happiness because they are happy. The one thing I might suggest is that you request to have a friendship with the guy. That way, you can keep yourself in reality rather then creating all sorts of fantasies about him in your mind. He's only just another human being after all.......
The key to life is in being fully engaged and peacefully detached simultaneously and authentically in each moment.