Hi Danioboy! :)
Welcome to the forums, and well done for having the confidence to share! Talking about problems with others is the most effective way to deal with them, in my opinion.
I'm coming at you from the other side of the tunnel- I've been through this exact situation when I was a little younger, and it sucks. And so, let me tell you that basing your self-image on one woman is not a crazy concept- in fact, it is EXTREMELY common for men to do this!
I was absolutely consumed by an attraction to a girl who did not reciprocate those feelings for three years! She was and still is an amazing girl, but I was young and not the person I am today.
Now get ready for the lecture. To beat a dead horse- you should work on yourself, and your purpose and the women will fall into place. When I was hanging around this girl, my purpose in life is the last thing I was interested in. I see now that this is what makes males attractive- a sense of direction and confidence. Trust me when I say that if you have these things in place, your physical attractiveness does not matter.
Basically, what I am saying is- that you should work on your self-image! It's important to note that this is not something that will fall into place in your life- you need to actively work on it to get better.
- Work on your physical health- go to the gym, go for running, eat healthily.
- Decide what you want to pursue in life- make steps towards achieving this goal (ie. what you might need to study, etc.)
- Pursue fun hobbies- do you play music? Do you enjoy hiking? not only are these fantastic ways to improve your self-image, but they are also great ways to meet women too ;)
There are more thing that you can do to improve poor self-esteem, which I can happily tell you, but I feel like the above items are the basics that you should choose to work on.
Please don't hesitate to ask any more questions! Having gone through what you have, I think I know how you feel. What I have told you here is a very abridged version that has taken 2 years of my life to understand. I would love to help you, so don't be afraid to reach out!
If you enjoy reading, I would highly recommend: No more Mr. Nice Guy (Dr. Robert Glover) and Awaken the Giant Within (Tony Robbins).