How do I find people to talk or vent to who aren't involved in my polyamorous network?

I have recently added a new partner to my relationship and all three of us are very happy. But I feel alone even though i have them. Everyone needs a friend to talk to but I just don't. My parents are horrified of the idea of being Poly, and when I tried to talk about it, it ended up going terribly, so I can't talk to them like I usually do. and since both partners are in the friend group we don't want to make it weird by telling them about the relationship. I feel like I have no one to talk to.

First off, kudos to you for wisely recognizing that sometimes venting and advice and just talking-things-out needs to happen outside the bounds of a polycule. I’m sorry to hear that you don’t have that kind of social outlet right now. But it is find-able!

Try going to polyamorous meetups in your area! They aren’t all for finding new partners: some are book clubs, discussion circles, board game groups, etc. and the point is for people to find like-minded friends to get advice and support from! You can also try polyamorous forums and chat rooms online - everywhere from reddit to discord has chat, advice, support, and general socializing for polyamorous people.