i understand your feelings. when i stayed in the past i was not able to get to the future. we all have done things we regret terribly. but we can't change the past but what we can do tho is learn from it.
your job frustration is i'm sure very discouraging. it can cause you to feel "less than". but you are not! when i'm feeling down i try to take the focus off me and help someone else. it turns me around and my perception about self improves. don't know why but for me it works. this thinking may help you in your job search.
imho, if we feel we are a loser it's a self fufilling prohecy. that may affect how the interviewer sees you and limit possibilities. instead write down a list of how others perceive you. like loyal, trustworthy, a good friend...read it before an interview. read it everytime you beat yourself up. being honest with yourself re what others see in you will turn the negative into a positive. it's hard to acknowledge what others see in you as worthwhile so you may have a short list at first. when i did this all i wrote at the beginning was my dog loved me!!!hope this helps.