Seattle has a poly meetup group: http://www.meetup.com/Seattle-Polyamory/
And I think the poly potluck still happens at the Center for Sex Positive Culture: http://thecspc.org/
Disclaimer - I haven't been involved in either of these for years, but attended both when I first started out and people were very helpful.
My only advice at this point is that if you're only 6 months out from big relationship problems, go very very slowly and make sure the existing relationship is truly healthy before you start adding more people to the mix.
- Moonlight, single, leans monogamous, girlfriend since 6/2012
- Punk, married guy, poly, FWB since 9/2011 with an emphasis on the "F"
- No longer lives with ex-boyfriend Fly (1/2006 - 12/2013, my introduction to nonmonogamy, ultimately amicable breakup), and his 11-year-old son Kiddo