I'm going to break up with my depressed boyfriend
What is your reason for wanting to break up with him?
He just doesn't make life worth living.
If they are going through a tough time you need to be there for them. You can make their life a lot better by just trying to get them help.
I think I need a change and need to start living my life for me.
Well, sometimes you do need to think about what is best for you. Try to also put yourself in the shoes of your partner though. Maybe you can find a balance between taking time for yourself and not walking out on your partner during their time of need.