Welcome to our forum.
I agree with you that it's important for you to get a chance to meet your wife's new boyfriend. I am glad she has agreed to a time and place where it will happen. Hopefully you and this other guy can get together (presumably on a platonic level) more often after that initial meet-up at the party.
I think it will take some time to establish the kind of poly life you really want, so exercise patience. Communicate a lot (and practice getting better at communicating).
Ask your wife for extra time with just you and her if you need it. Often when people get caught up into NRE, they don't even notice how it's affecting their pre-existing partner.
Read many threads here, and post many thoughts and questions as they come to you. At the moment, you seem to be proceeding in a pretty sound way.
Glad you're aboard,
Love means never having to say, "Put down that meat cleaver!"