Hi Ga,
I think adding carbon was a good idea. If you can, you might want to do a moderate water change. Caulerpa produces various toxins. C. racemosa isn't really nasty compared to some other species but these toxins could harm your tank. Do you have a skimmer? If so you might want to crank it up (if possible w/ your model). I would leave the parts that still look healthy. How big were the pieces that went sexual? FWIW, when caulerpa self-destructs like this it is reproducing sexually. It breaks down its protoplast and turns it into gametes.
One way to reduce the likelyhood of Caulerpa trying to reproduce sexually is keeping the main horizontal 'stem' right around 12" or less. When you cut caulerpa you should only cut it at one place at a time. Caulerpa is actually one giant cell (it's a siphonous / coenocytic algae) so when it is damaged a lot of the cell contents can spew out a wound. Some people say keeping Caulerpa under 24/7 lighting in a refugium will prevent it from going sexual. I have 24/7 lighting over my refugium and my Caulerpa has never gone sexual but that, of course, doesn't really prove this theory... it just coincides with it. I do try to keep individual 'plants' shorter than 12". If you have had it with Caulerpa, other algae that are good for growing in 'fuges are Chaetomorpha and Gracilaria. These algae do not reproduce sexually like Caulerpa and are non-toxic.
HTH & Good luck,
Kevin