I'm crashing out and not in nursing program yet

I haven't even made it to the nursing program yet and I'm already crashing out. I'm in Anatomy and Physiology 1 and it is kicking my ass. Typically the class spans an entire semester, but I was a huge dumbass and took the summer class that lasts 6 weeks. The homework and material feel fine but the tests are so hard. I'm working 45 hours a week and trying to juggle this ONE class. Genuinely feeling like a failure. If I can't handle this pre-req how the hell am I going to manage anything else?

My boyfriend has been supportive and said there's no harm in retaking the class but I feel so ashamed at the idea of getting my degree even later. I'm still passing the course but with finals this week, I can't help but panic.

Thank you for coming to my rant.