I can't understand why your boyfriend feels that your loack of public affection makes him'feel bad about himself'.
If people don;t feel like kising etc. in public, then fine, i fail to see there is a problem.
If your boyfriend feels he has to demonstrate to all and sundry that you are together by PDA's, then that is down to his insecurity.
If he is threatening you with breaking up unless you change, then let him go ahead.
This man is too controling, and if he has no more repsect for you than to allow for your feelings, he is not the boyfriend for you.
Ditch him, and find someone who is worthy of your time and attention, and who will understand your prefectly reasonable desire to save your affection for your private times.