I understand the 'not sharing' but in my own family I have seen the enormous difference when one decides to finally share that baggage. It literally lightened this person's psychic load to the point she was physically less impacted by her anxiety. Read through the thread and saw your further thoughts and comments.
Again, I have experience dealing with this within my own tribe...besides the anxiety and depression (both major of course) sounds to me like you have to start liking yourself a bit more and giving yourself permission to
be liked
make the off mistake
not be perfect
try your best as best can be
Sounds easy but I have seen how hard it is. This is different to being a narcissist, it is simply about allowing yourself to be treated as a normal human being. Not sure what happened to put you in the 'guilt space' but whatever it is, talk about it with someone (I'm sure you are) and have them help you realize it is not yours to carry endlessly through time.
It reads to me like you're not doing yourself justice in the relationship to allow the relationship to be one where everyone is happy. Your good lady can only walk through the door if you open it, and you will only do the relationship justice if you give yourself a break, embrace your flaws and realize that despite all that you must be a pretty great bloke because hey, she ain't there for the food, she's there because she likes you!!!!!! Let that settle in. Give yourself permission to acknowledge it mate.
One other thing before I go...it is NEVER the 'problem' or 'mistake' or perceived 'fudge-u'...it's how you respond to it/them. Because mate, we ALL run into them. It's being human. And it's also being human to not only accept the responsibility and learn, but to recognize that it is OK to walk that path, you're still a good bloke, that many many people do and that it is a part of all our lives.
Good luck and COYS