The feeling of despair and hopelessness may seem very appropriate and particular to your situation, but you should know that others have been there and have suffered similar or worse experiences. They have survived to enjoy life and so will you.

"We shall draw from the heart of suffering itself the means of inspiration and survival." - Winston Churchill

All things pass, have they not always before? To counteract the feeling of hopelessness, list those assets and pleasures which you have but seem to be ignoring. Perhaps some of these words will turn your thoughts: family, friends, health, job, home, nature, pets, garden, music, faith, books. Start thinking about the nice things in your life, things you value and make you happy. Leave the negatives behind.
 
"Who will tell whether one happy moment of love or the joy of breathing or walking on a bright morning and smelling the fresh air, is not worth all the suffering and effort which life implies." - Erich Fromm

The feeling of guilt often results in despair and depression. We should think about the wrong we have done, but just long enough to realize the full extent of what we did. If there is something that can be done about it, consider doing it. The only other thing that we can do is to assure ourselves that we will avoid that mistake in the future. Beyond this, stewing over it and rehashing the event endlessly, will do no good. It is a complete waste of time and makes us feel sick with worry.

Avoid experiences that result in guilt by not judging, blaming, or bringing down other people. Try to find their good points, and try to avoid anger. Be nice to yourself too, accept that you make mistakes, and don't hold a grudge.

One of the best ways to recover from despair, guilt, or sorrow, is to keep busy.

"When all else is lost the future still remains." - Christian Bovee (1820-1904)