Break up during school

My boyfriend and I have been together three years and we we have been living together for over a year. He left me out of no where while I was dealing with my own parents divorce. Now I’m dealing with losing my apartment with we got together and losing him. I am extremely heartbroken and I’m falling apart, and I start classes in two weeks. He claims he doesn’t want this anymore when not long ago he wanted me in his life forever. Has anyone ever experienced this and does anyone have any tips on getting through this during school… He was my main support system and my best friend. He’s been there for me since I started school and we were even planning on getting married. He threw everything away so easily and it’s really hard to except. I know a lot of people go through this, but right now it seems impossible to handle this much pain and take these hard classes at the same time.