Welcome to the forum.
I have to agree with Geoff, you are not different because you and someone else find they cannot make a life together. Why do you think this man rejected you because of whatever happened in high school? If after a year together he has not decided to he wants to stay with you I would suggest it is more a matter of incompatibility rather than being shocked by your past. After a year he should know what sort of person you are, trustworthy, loving, caring, happy etc.
The reality is we all have skeletons of every sort in our various past lives. These do not automatically make us less worthy of love. It is simply your past life. I also wonder why you felt the need to to tell this man your history. Did he tell you what he was like growing up? Although you have not told us what happened in high school, and there is absolutely no need to do so, it's probably no different or worse than the activities of others.
I suggest you go out into the world and meet other men. Be picky with who you choose and perhaps keep the details of your past to yourself. There is no requirement to reveal all. It's your business not that of anyone else.
I'm not sure what you mean by "work on myself". What sort of difficulty do you have or do you mean you need to improve yourself in some way? As we grow up we are constantly changing what and how we manage. It is the maturing process and I think it continues all through our lives. As long as you are aware of yourself and the impact of what you say and do, plus the desire to change or alter your behaviour if it hurts others, then welcome to the human race. We are all flawed people.
Please carry on your life and learn from any mistakes you make in order to do better in the future. Do avoid self blame. None of us are perfect. What makes us attractive to others is the willingness to improve ourselves.