Feeding schedule stress - formula vs breast

We're 6 weeks in and my wife is struggling with breastfeeding. She's got cracked nipples and it's painful. We've been supplementing with formula but now she's worried about switching completely because everyone keeps telling her breast is best. I just want her to not be in pain and our baby to be fed. Why is this so complicated? Can someone just tell me if formula is actually okay without the guilt trip attached?