Clinical Depression and the Moral Permissibility of Suicide

I detect a cri du coeur in the following  question to me from a reader:

Do you believe it is morally permissible for an unmarried person who is now middle-aged (late 40's) and who has no children to care for and who has battled clinical depression and anxiety for many years to commit suicide?

Since this is an 'existential' and not merely a theoretical question, and because I want to treat it with the proper respect, I should say that while I have read about clinical depression, I would not call any of my bouts with anxiety and depression 'clinical.' I  have successfully dealt with all of them on my own through prayer, meditation, Stoic and other spiritual disciplines, journal writing, vigorous physical exercise (running), and just toughing it out.  The classically American virtue of self-reliance, too little practiced these days, can sometimes see you through much better than drugs and hand-holding.  But I have been spared the hell I have read about in William Styron's Darkness Visible, and more recently in the philosopher J. P. Moreland's Finding Quiet: My Story of Overcoming Anxiety and the Practices that Brought Me Peace.  

I recommend Moreland's book to the reader and this interview as an introduction thereto.

To come directly at the question: any philosopher who proffers a confident answer to the question is either a fool or a blowhard. Being neither, I will say that I don't know.  I further believe that no one knows despite their asseverations to the contrary. I will say that I have never seen a rationally compelling argument against the moral permissibility of suicide when the going gets unbearably tough.  That life is hell for some people is better known than any doctrine that forbids escape.

I now refer the reader to some entries of mine that I hope are of some use to him.

On Suicide

Kant on Suicide

Benatar on Suicide: Is Suicide Murder?

Is it Always Wrong to Take One's Own Life?

Suicide, Drafts, and Street Corners 

Addendum (1/28). It seems to me that each of us who has the time and soundness of mind to pursue the question should should decide now what he will do if calamity strikes.