You’re right. You do need help. You made a common mistake. You thought dependency was love. It’s not. You and your boyfriend both have trouble making friends, dealing with feelings, and liking yourselves. In each other, you each found a person who could understand and you clung together to make things seem okay. Things weren’t okay. You’re still not okay. I imagine neither is he.
I don’t have enough information to even guess why you got to 16 with so little sense of self and such low self-esteem. Something is lacking in your education about how to get along in the world. Somehow you didn’t develop the skills necessary to deal with the social scene or your own feelings.
The good news is that you are young. You haven’t wasted 40 years sitting in this pit of self-dislike. With some therapy, you can learn to love yourself — which is, after all, the first requirement for finding someone who can love you. Please talk to your parents, your school counselor, or doctor, or clergyperson to get help in finding a therapist who likes working with young people.
It was brave of you to write your letter and to ask for help. Now please do the next step and get the help you need. I suggest you take your letter with you to your first session. It will help jumpstart your work with your therapist.
I wish you well.