Welcome to our forum.
I didn't really plan on getting involved with polyamory, I just found myself in a polyamorous situation. I am now in a poly unit of three people (a V); it is polyfidelitous, so we don't have sex outside our poly circle, and we're not looking to expand it although we're not fully closed to that idea. Not quite the same as your situation, but similar in that it wasn't something I planned on beforehand.
Our unit is fairly conservative and we don't do a lot of talking about one couple's romance with the other couple. Other than that, I'd say most of the stuff we've learned, we've learned through experience. We've been together since 2006.
I'm sure you'll find there's a great variety of polyamorists on this site, including some with a situation similar to yours. You can do searches and tag searches if that will help. Otherwise, just look around at our various threads and see what thoughts or questions they raise, which you can post at any time.
I'm glad you could join us.
Love means never having to say, "Put down that meat cleaver!"