You didn't mention this but based on what you've said your boyfriend and you are living together, correct? If that's the case, then did you talk to him about leaving college on your last semester? Perhaps he feels like all of the financial burden has been on him for a while and now that you won't be finishing school this semester it's going to continue until you decide to go back.
Don't get me wrong, I think he is going about this the wrong way-- being mad and almost throwing adult tantrums when he goes through his funks is not the way to solve this but it's clear that something's up.
You, being an adult, need to sit him down and explain why you left on your last semester. Then reassure him that you will be going back next semester, finishing, and then helping him with financial responsibilities. I understand that you needed a break, I felt that way many times during nursing school, but when the burden is placed on someone else and you share your life with this person, you MUST take their feelings into consideration.
Talk with him, get it all out in the open, and keep us posted,