Ok, addressing these one at a time. Ks backstory is.. complicated. She's been in a relationship with another woman (I'll call her C) since they were both teenagers. In this 10 years time K has had a handfull of male lovers, and one you might classify as a boyfriend. She is still with C, but I don't know much about their inner workings. I suspect that K ultimately wants to be with a man. Hence the whole babies thing. And I think, whether she even knows it or not, that she wants a man to be her primary while having a female secondary or tertiary. I don't know if she wants my husband to be her primary.
K and R, my husband, have had a pregnancy scare already, and seemingly another scare on the way. (Apparently condoms aren't as reliable as they used to be) And they were both upset when the test came back negative. I was relieved. Not that I don't want this for them, I still don't know what I want there. But I fear I am not ready.
And I fear, as FlameKat said, that this is all too fast. Swirling emotion and all that. I mentioned this to R, and he acknowledges it as a possibility but doesn't show any sign of slowing down.
He and I have discussed that if they decide to try for kids, they have to tell me BEFORE they start. And we also have discussed each of us being tested for STDs and the like before they cease protection.
As for the cohabitation, they are not asking for it yet, however R has stated that if he and K get pregnant she will be living with him. End of story. Now that could be moving her in with us, him in with her and C, or the two of them alone. I don't know. But i too feel this is moving way too fast and it scares me in more ways than one. Of course I'm scared for me, and my marriage to R. But I'm also scared of him getting hurt. And adding a baby to that possibility of hurt is even worse. But it's hard for me to articulate to him, without it coming across as me finding reasons for him not to do this with her, for my own benefit.
As for 'cowgirl' I don't know what that is, but I will be looking through the forums for it now.
Thanks for the replies and the links to other posters. I appreciate the help and the love. If you want more info on this story, please ask. I'm still so new I don't know what be something important that I've left out.