Sore n cracked nipples are quite common for first time bf moms. Just tell yourself to be strong n hang on. After 3 months of bf my baby, my nipples r used to his sucking, pulling, and whatever torture! Lol. Now it doesn't hurt anymore as my nipples r 'seasoned'.
I use nipple cream, rub some breastmilk on the nipples and air dry my nipples at night even though they leak milk. Try not to use a shield that prevents air circulation. Air drying and the breastmilk helps to heal cracked nipples. Baby dont't latch very well at first so such problems comes up. Be patient n let baby learn to latch. you can help baby n yourself by reading up breastfeeding books like 'successful breastfeeding' by Sister Kang of Mt Avernia. I read that like a bible before my child was born.