Things with my gf recently ended as well, and while we weren't together as long as you were with yours, I definitely feel your pain. I too was in a situation where the relationships and lives were entirely separate. My gf reached out to my wife a few times in subtle ways, sending gifts for her, offering me relationship advice, etc. She was supportive, for awhile.
I think everyone spending time together is important. It hasn't happened in my poly yet, between my wife's lovers, or mine, but I hope for it.
My GF wasn't really into the poly thing either, I'm starting to think that it's a more important component to a functional relationship than I previously did.