My boyfriend broke the skin while sucking/biting my nipples, the skin is cracked and very sore and painful, what should i do?

Clean it: Human saliva is loaded with lots of nasty bacteria. You need to wash it, apply antibacterial ointment, put a bandaid on it and ask your BF to use a little restraint in the future! It's going to be sore for awhile.

Keep clean.: Treat like any other cut, and clean with dilute soap and water and apply a light coat of bacitracin and a bandaid twice a day. Use an unscented soap. Take tylenol (acetaminophen) for the pain, ibuprofen if it's been more than 72 hours since it happened, too, if needed. Is your tetanus up to date? If not get a booster within 2 hours. If the pain gets worse, or if you have redness, pus, fever, get checked now!

Clean and dry: Keep the area clean and dry. It should heal up in a few days. If you notice increasing redness, see a doctor, because it may have become infected. Hope this helps!