Hi Felfin,
I really feel your pain. I know how terrible it is to be unable to breathe. In 2009, I had a severe TB infection (probably due to immune-suppressive drugs) added to my stage 4 sarcoidosis, which caused fibrosis in both lungs, allowing me to only use 50% of my lungs' capacity. I also had a pneumothorax, which kept me in bed for 6 months (the infection spread in my body, and I was taking 35 tablets a day). I also had a drainage tube installed in between my ribs, which is quite painful when kept for months. I was on oxygen therapy for about a year - there were days when I couldn't breathe without supplemental oxygen, not even for one minute. I remember that the first thing I used to do in the morning after waking up was to cry for half an hour. Anyways, the TB was cured after one and a half years - yes, I took those strong medicines for 18 months; they used to make me so seek....- and suddenly, sarcoidosis and fibrosis stopped. I have been stable until this year, when they saw some new lesions in both lungs, which means that either sarcoidosis or TB is back. Unfortunately, I had a rare type of TB, which cannot be diagnosed through sputum (I have nodules with infection, without sputum), so we are just guessing. I have two doctors, one telling me that it is sarcoidosis, the other one saying it is TB. So, God knows, really. But, I am not depressed. 
When I stood in the hospital for three (endless) months with pneumothorax, sickness, complications, pain, and depression, I understood one thing: life is not ours; it was given to us, as a gift; a gift that we have to return one day. Since then, I have lived my life the best I could - without making any excesses. I know it is easier to say than do, but I am the living proof that it can be done. I take care of myself, and I work really hard, although I have a state pension - working makes me forget my situation. You should also get involved in a hobby or something.
For instance, I love writing; I always wanted to become a writer, and I decided to start writing articles. Now, I have a couple of clients who send me enough work to keep me busy and away from negative thinking. Find something that you can do - I know, it is hard to concentrate, but you can do it. I have days when my mind is spinning is a big, black cloud; usually, I use those days to write, and the next day to revise what I wrote the other day. It works.
Unfortunately, since there are no cures for many diseases, including sarcoidosis, fibrosis, certain types of TB, etc., the only thing we can do is to hang in there and learn how to cope with the situation. I think about those kids - 16, 17, 18 years old - who have leukaemia. Besides physical suffering, they are mature enough to understand the fact that they will never graduate, they will never love, they will never get married, and they will never have children. We have been given the chance to live much longer, so, I guess, we cannot ask for more. One more thing: I feel lucky that I have this disease instead of others, much, much worse than TB, sarcoidosis, or fibrosis; for instance, Lou Gehrig's Disease. So, I have chosen to live my life, regardless of how good or bad it is, instead of feeling sorry or regretting that it will end too soon. I'm not saying that I'm always happy, smiling and feeling fine. I have my own moments of sadness, but I don't let those moments to invade my world.
Eventually, every man's life ends, and we can't do anything about it. You have a husband and a son. You should try to spend the time you have left for them, with them. I hope you will find the inner soul strength to do it. Believe me, you will feel much, much better...