Originally Posted by purelyparadox23
which I didn't realize until after I'd been seeing him for a few months.
This is the disturbing part of your message for me. He is not communicating honestly. He just happened to forget mentioning this other person?
And getting married to a mono while being "poly" with you doesn't sound poly at all - more like he wants to eat his cake and have it too.
It doesn't seem like you're going to get your needs met here.