Trust is a very diffiult thing to build and so easy to tear down. I think you need to ask yourself do you still want a marriage, I'm guessing you would say yes or you wouldn't be looking for advice. I think you need to adknowlege her fears/concerns avoid situations where she will have a chance to doubt you, and expect any repair in your relationship to take time. There have been a couple of times I was in total dispair because I thought my marriage was over, but each time with time and honesty things got better. Tell her you want to make things better, and let her assist you in working to make things better.