Well, we have all made mistakes... we are human, we try and learn from them. The problem is, your boyfriend has serious self confidance issues, seems like he sufferes from anxiety (or could even be depression). I know this, because I suffered from depression, which was caused from anxiety and lack of self confidance. I saw a phycologist, and it does actually help. What really didn't help me (everyone is different) was pitty and sympathy, because it made me feel sorry for myself, but reasoning, I managed to find a shrink who was able to reason and explain my feelings, and try and work out ways to counteract them. Although my problem didn't lead to problems in the bedroom, it led to complete isolation from the outside world, which in fact made me lonely, and stuck for being able to socialise with people. Especially girls, I'm extremily shy when I meet girls, but I've waited, and I might have found someone special...
But, I'm babbling...
Talk to him, tell him, the past is the past, and the future is there for the taking! He obviously loves you to bits, hense why he is with u, and you obviously love him, as you are asking for advice. So try and get him to relax more, open up a bit. More than likely, he is using your past to blame, so he can keep his problems bottled up inside...