If you were my teacher, would you be forgiving/understanding?

This is what my chemistry professor would call "emotional blackmail." Seriously though, if you knew this C was so important, you should have put more effort into your math class. If you were having issues for two whole years, you had plenty of time to explain that you were having problems at home that were affecting your school work waaaaaaaay before your very last final of your very last year of school. He might have gone easier on grading or let you turn some assignments in late. You can imagine how bad it would look begging for a higher grade after all this time has passed since the problems began and you had plenty of opportunity to come to him. Grades are earned, not negotiated. With or without your family issues, you earned a D. Take this lesson with you to college: you can't just ignore it if you're struggling. It is very important to ask for help if you need it, and that's what teachers are there for. You're going to get eaten alive in college if you don't speak up when you're having trouble.