We all make mistakes regularly. Welcome to humanity. Now that we have that out of the way, the next thing is how do we handle this without beating up on ourselves and injuring our own self-esteem? Life is for learning and nobody needs to be hurt to learn. So be nice to you is my first bit of advice.
In keeping with that my second bit of advice is you should seek out a counselor and spend some time in talk therapy. You need to talk about your feelings related to self-esteem and perhaps other pertinent related things with a professional where you'll get the best help you need. This is not about any sort of weakness or deficiency in you. It's all about the very real need that so many of us have at times in our lives for objective guidance and support in finding our own answers and growing as we do so. I can tell you need some support in building up your own confidence, self-esteem and sense of self worth.
Happiness and fulfillment in life are things that spring from within, not from without. You won't find them in a relationship with someone else for example until you first find them within your own self. When you cross that bridge then you are ready to be in a healthy loving relationship and you won't need this old man to tell you so on a message board. You will know.
A good counselor or therapist can help you get to this good place and I would sincerely and highly recommend you get on the phone Monday and make it happen. The sooner you are working on this with someone the sooner you are heading for feeling good about you and you really do deserve that. I know you do and I believe that you can come to know it too.
Don't know where to begin? Ask your own doctor if you have one for a referal. If that is not an option, open up the yellow pages and make some calls. If like me you believe in God in some way, don't forget to ask him to help you find somebody good.
Lastly, you might like to read some books with nice daily affirmations that are wonderful for helping one to focus on positive things about themselves. I know you can find such books at any good bookstore and probably the library too.