Thanks for explaining further, Tempestseeker! I'm another one who would take a chance and see the GC. After all, as others have said, once the split is compete, DS will probably have some visitation and be able to share some of his time w/ you. Even if he gets back together w/ P and she finds a reason (or "reason") to cut you off again, chances are, things will change again as time goes on. In fact, you may be the main source of stability in these children's lives, so I think I would be there for them whenever I could.
But if you're too uncomfortable w/ the idea, I would at least send cards and gifts, as some have suggested. Please try to keep some kind of contact and give them all the love you can.
As far as DS' romantic history is concerned - IMO, some posters are being overly critical. It's not unusual for someone to begin a new relationship before a previous one is fully over. In fact, I believe that's very common. In the first thread, it did seem as if you were critical of P for being the girl that DS left XDIL for. Do you think she sensed this and that if affected her treatment of you? I'm also not clear on whether or not following her rules for her kids has been part of the problem w/ her. Do you feel she's "too rigid" (my words) perhaps? And that you just can't observe her rules, and so risk another CO? If you don't feel comfortable w/ her rules, that might be another reason for doing no more than sending the GC gifts, etc.
I've got another 'keen'... Ouch!