Hi Chatty, so sorry to hear your dp is giving you so much grief. Now I may be a bit controversial here but my thinking on this is; do your utmost to show him how strong and together you are. Some might say that's pandering to his insecurities, but I think sometimes men panic at the responsibility especially when faced with an emotional weepy hormonal woman (I'm not saying you are that woman at all, it's just that sometimes we can all be a bit like that if we're honest with ourselves). He's probably attracted to this other girl because right now she's fun, she's carefree, she's independent, she's up for it. Now of course you can't do anything about the fact that you have a ds and another one on the way, but you can show him you don't actually NEED him (even if you do).
I think (and maybe I'm totally wrong on this, feel free to disagree) that men find clingy desperate women a real turn off, and a strong, attractive independent woman a real turn on. So in this case, my plan of action would be to hold it together as much as possible, don't even mention the situation, pretend like you're not actually that bothered cos you know, if he left, you wouldn't actually collapse and die! Always look your best, don't show your vulnerable side to him, that's what girlfriends are for. To paraphrase James Bond, never let them see you bleed.
Reading this back it all sounds really harsh, but I've always believed smart girls don't play in to men's expectations that we're all weak and emotional and we desperately NEED them to hold us together. Maybe deep down some of that IS true, but I don't see why we have to let them see it. If we do, we give them every reason to run away and hide from their responsibilities.
Maybe I'm totally wrong on this, and feel free to totally disregard everything I've said. It's just how I'd play it.
I hope sunday night goes well, glam yourself up girl, be the woman he wants, laugh alot, have fun, talk about fun things, talk about some great things you can do in the future before you discuss your relationship. Let him see that the future with you and your kids doesn't have to be endless drudgery with no fun. You don't particularly want that either!
XX