I feel like breaking up with my gf due to her depression
Why break up with her when she needs you the most?
I think people with depression are broken. My gf's attitude after becoming depressed is completely different.
I understand that much of a change makes you want to leave, and ultimately if it's bringing you down that much it's your decision. People can leave relationships for any reason they see fit. However, it would probably make the situation worse for her if you were to abandon her.
Why does she have to be so sad and what's the matter with her anyways? Why does she need to be taking more drugs?
It's hard to understand depression. What you need is professional help to help your gf. You can't do it alone.