What can I do?

My friends constantly want to hang out and do things almost everyday - which I do not. I'm a homebody and I rather go out twice a week. They don't understand that I battle with depression, I rather be along because that's what I'm accustomed to. My roommate said I was being a brat because after working 50 hours a week, I just want to go home and do what I want. I feel like I have no time to myself and when I finally do other people take up my time. How do I explain this to them?