I Suffer From Depresion

I have friends and family and they are wonderful. But I feel so alone most of the time. Then I feel ungrateful and guilty for being so depressed and anxious. Even though I know logically that I can't help it sometimes. Other times I'm able to fight it. My thoughts turn to suicide but I hide it all the time, not wanting to worry anyone. I thought at this age I'd be sorted. I thought I'd be strong and confident and that the illness that plagued me since childhood would be gone or at least I'd be a lot better. In some ways I am, but still this lonliness persists.