Worried :/

I've been dating my SO for almost a year..He has Bipolar Disorder and ADHD. These past couple of weeks he's been really depressed and has a little bit of anger. This is the first time i have seen him depressed our whole relationship and im worried about it. He's always been sweet to me and respects me, and still is, hes an amazing person... It's just his depression and slight anger worries me. He is on medication for his Bipolar Disorder and i know how to deal with mental illness because i have OCD and PTSD and every now and then get depressed.... but i just hate seeing him like this... I know he cant help it.. He has a lot going on in his life right now.He's 20,is in college 5 days a week and works 2 jobs, he lives with his parents and i know that stresses him out A LOT. He's trying to save some money so that he can get out on his own, but rent is expensive here. He's also always letting little things get to him, and i try to help him see that those things that get to him aren't AS important as some things. And he always tells me im right about it, but then goes back to dwelling on those things. He came over today after class and he just seemed so out of it. He then told me he didn't go to class and just started crying. I just tried talking to him and supporting him like he does for me. It just breaks my heart to see him like this. IM used to seeing him happy..Im afraid for him. He told me a week ago he was having suicidal thoughts... I worry about it. Constantly... I honestly dont know what i would do if he did that... I would be so screwed up. I try and show him that i love and care about him,,,, but im afraid thats not enough sometimes He's literally my rock and i try to be his in return.... But i can only do so much for him. I wish i could take all the pain away. But i cant.... Im at loss...I just want to help him and i dont know how..... it breaks my heart. What can i do to help him?