I'm not sure you'll find many others of your persuasion here. I don't mean that in a funny way, just that it isn't a mainstream lifestyle and so statisically speaking you are prob best off finding a specific 'poly' forum for your more specific stuff.
Of course on MN all parenting 'types' are welcome just you may find it difficult to have discussions with other polys on here, because I'm sure we have any! Hey, you could start a new trend on here. LOL
I am really not having a good day. To cut a very long (2 year plus) story short I made the dreadful mistake of sharing some information about my lifestyle with a married couple I met at a meeting down in London. It all seemed very innocent but basically I was duped by them into letting them read a blog I was writing and sharing with a handful of friends. They took to posting verbatim extracts of my blog to people I didn't know at all encouraging these people to register a protest by email at what I was doing. I was stupid enough to not change my email address and try to reason with them. Then it got a bit worse because changed versions of what I had written started to get circulated. Nasty changes too intended to upset me and outrage any reader. Also lots of emails which I used to think came from different people until a dear friend showed my how to prove that over half had come from the same computer. In the last couple of months a very well thought out campaign has gone on. 100% legal by the way but nasty and vindictive. Very carefully designed so that nobody can trust what they read and nobody can tell bizarre fantasy from reality. Readers then gets bored with all the rubbish that appears and move on leaving me with nowhere to turn for advice or help.
You're probably not the only one here TBH. I am poly-friendly (though single). Sorry you are having such a rubbish time with online harassers (can't help wondering if one of them has a name that begins with J, because an individual in an open relationship with a name that begins with J gave a friend of mine an appalling amount of grief last year). WRT the going-public-or-not if you have an uunusual lifestyle, I am still sort of blundering through it myself. It wasn't untill I started going to toddler groups with DS that I realised just how much of my time had been spent in 'unusual' company, and how hard it was to deal with the 'normal' world.