Try reading and following The Power of Positive Thinking by Norman Vincent Peale. Because I am not religious, it doesn't do a much for me but it is a worthwhile book and I think it might help you.
As for your son, I don't know how anyone raises 2 boys as a single parent. He's 14, right? A rough age to cope with. Even worse when you are depressed. He is at an age where he will have no sympathy for tears and depression and may instead use them to his advantage. Not because he is a bad kid, just because he is a kid. I always found lying the hardest to take. Try to get through to him that you will support him in trouble but he has to be honest with you. These are hard years coming up for him and for you. My younger son was 21 before I finally stopped feeling like it was my fault every time he screwed up. Good luck. Keep talking, even about kids. Many of us have been there.