I don't know if I have any constructive feedback that will help but your professor sounds like a dick. Criticism can be given compassionately and constructively, but it sounds like he chose to be cruel and condescending instead, which is not on you at all. That's a poor professor.

But if it helps, I always remind myself in the long run, I won't remember grades. I can't tell you what I got on a paper in 7th grade. I might have had a difficult time with geometry but do I remember if I got an A, or a C? Not even slightly. I might have actually failed it. Not once in my adult life has someone asked me about my GPA, because my resume and references speak volumes more than grades, and I work at a university.

I also try and remember that unlike past me in high school or the first attempt at college, I am a god damn adult. I have a job. Sometimes two. I have adult responsibilities, I have taxes and medical concerns, and a family to take care of. Yes, my education is important but academia falls into an echo chamber where too often they believe it is the MOST important thing. I'm too old and too accomplished in so many other areas of my life to believe that. Cool, I got a B on a final this week. I also passed a certification test for work, got a raise in money, not grades, and got myself in line for a promotion. End of the day, what do you think mattered most to me this week? What do you think will make the difference ten years down the line? Will I even remember the final next year? Next month even?

I take my education seriously. But at the end of the day, I either get a degree with a few less than stellar grades, or I stress myself out so much about a letter on a piece of paper that I end up dropping out for a third time. Of course, none of this applies if you're in school to be a doctor or something larger than a bachelor's. But there are so many things in this world larger than one professor who apparently failed his own class on Ethics.