I've been thinking about all of you a lot in the last week, RP, and pondering the ups and downs and challenges of family life and relationship changes. It seems to me that all of you are exceptionally courageous in that you've chosen to meet more challenges head on than most. That's probably why I like you.
One thought I had regarding the situation with you and PN is that this might not be directly related to you being poly, but more about how you both expect and require your needs to be met. I can see how overwhelmed PN is feeling, emotionally, and how difficult it is for you to balance your care for him with your desire to look after your own, legitimate needs. My offer still stands for this weekend, btw.. (Now I'm imagining you in your van all cosy, heh.)