In terms of reaching out to him, my advice would be just to leave it for now you have tried your best and he is not interested right now so you will be kinder to him by respecting that. Life works in weird ways and it could be that you will bump into him at some point many years in the future and will have grown/changed and he will know you are sorry. Or maybe that won’t happen but the lessons you learnt this time are part of your life path for meeting future people.