The issue is not so much your childhood or past trauma as the here and now and your own behaviour. Why are you still unable to realise that this relationship is over? You don't need this girlfriend, she has dumped you?
You are as you are. Full stop. Do not make any contact with her.
If you are focussed on yourself others will see this. Why are you so stuck on yourself as the important one?
That is a big red flag and many people are unable to accept rejection. How dare anyone reject you?
Do not make contact with this girl, forget her and leave her alone. Do not look for ways to make a road back to her. This girl is history and has no further part in your life. It is only in your own mind that this girl still exists as a potential lover. You are in danger of starting stalking behaviour because after six months breaking up, the time is far too long to be stewing over a broken romance. Two weeks to a month - allow yourself time to grieve your loss and move on.
She has decided you are words 'unmentionable' so live with it. She has seen a side of you that she did not like. Accept it.
Your issue is you believe you are still the one and she is mistaken, and you want to prove her wrong. So how can you remedy this? You can't.
Take time to work out why you you feel are more important than other people. Your early childhood and your upbringing may have an influence here. Then work at spending time and working out how to genuinely care for other people. Understand your own psyche and personality first.
Use the time you have to study, to partake in hobbies and find genuine friends and to understand why you might be so self centred. Move out into the world and take time to listen to others. Try to genuinely understand others and do not focus on one person at the exclusion of all others. This girl is history, and is a failed conquest. Now leave her alone.