Your pain is extremely evident and we all feel for you and hope you'll find healing with the help of Hashem very soon!
You are asking great questions and there are great answers to them. Before answering the questions it's important to put them on the side and try to heal the pain.
Long ago, Rabbi Nachman of Breslov had recognized Simcha as the key to success in religion and coming truly close to HaShem. In stressing the importance of Simcha he went so far as saying that depression - the antithesis of Simcha - constitutes "the main bite of the serpent (the Yetzer Harah)". How far should a person struggle to remain steadfast and avoid depression? The lesson is best illustrated by the following story Rabbi Nachman told to his disciples:
"But what is the antidote for the person who feels so heavy, so depressed, that no words of encouragement or advice have any effect?"
There was once a poor man who earned a living digging clay and selling it. Once, while digging clay, he discovered a precious stone which was obviously worth a great deal. Since he had no idea of it's worth, he took it to an expert to tell him Its value. The expert answered, "No one here will be able to afford such a stone. Go to London, the capital, and there you will be able to sell it." The man was so poor that he could not afford to make the journey. He sold everything he had, and went from house to house, collecting funds for the trip. Finally he had enough to take him as far as the sea.
He then went to board a ship, but he did not have any money. He went to the ship's captain and showed him the jewel. The captain immediately welcomed him aboard the ship with great honor, assuming he was a very trustworthy person. He gave the poor man a special first class cabin, and treated him like a wealthy personage. The poor man's cabin had a view of the sea, and he sat there, constantly looking at the diamond and rejoicing. He was especially particular to do this during his meals, since eating in good spirits is highly beneficial for digestion. Then one day, he sat down to eat, with the diamond lying in front of him on the table where he could enjoy it. Sifting there he dozed off. Meanwhile, the mess boy came and cleared the table, shaking the tablecloth with it's crumbs and the diamond into the sea. When he woke up and realized what had happened, he almost went mad with grief. Besides, the captain was a ruthless man who would not hesitate to kill him for his fare. Having no other choice, he continued to act happy, as if nothing had happened. The captain would usually speak to him a few hours every day, and on this day, he put himself in good spirits, so that the captain was not aware that anything was wrong. The captain said to him, "I want to buy a large quantity of wheat and I will be able to Sell it in London for a huge profit. But I am afraid that I will be accused of stealing from the king's treasury. Therefore, I will arrange for the wheat to be bought in your name. I will pay you well for your trouble." The poor man agreed. But as soon as they arrived in London the captain died. The entire shipload of wheat was in the poor man's name and it was worth many times as much as the diamond.
Rabbi Nachman concluded, "The diamond did not belong to the poor man, and the proof is that he did not keep it. The wheat, however, did belong to him, and the proof is that he kept it. But he got what he deserved only because he remained happy. *
It is up to each of us never to lose hope, and like the poor man in the story to whom everything appeared lost, force oneself to be happy. Even a faked, ungenuine, happiness, has the power to transform our situation and lead us to genuine joy.
But what is the antidote for the person who feels so heavy, so depressed, that no words of encouragement or advise have any effect? To the one who feels he has reached the end of his rope ... feeling so low and discouraged about himself that he can only term himself "dead." Rabbi Nachman throws a lifeline: He stresses the statement of the Gemara that in the future, Hashem will resurrect the entire body through a certain bone known as the "Luz". Invisible to the eye, the Luz defies destruction. Placed on a stone and pounded repeatedly with a sledgehammer, eventually the sledgehammer will break in two and the stone will shatter into a thousand pieces - but the Luz will remain intact and unharmed. "Thus we see," says Rabbi Nachman, "that no matter how low a person has fallen, there exists an indestructible part in him, that can form the basis for a new resurrection - a new life."
Focus on your Luz , advises Rabbi Nachman. Ask HaShem to help you find that indestructible part, that essence of yourself that no sin or misfortune can erase. Bind yourself to it. Concentrate on it. Allow it to gladden you and make you happy. Then, even if you find yourself in the deepest, darkest pit without the slightest trace of hope or light - still, you will always find your way out.