I think you know the answer to this.
Reread what you wrote and imagine your best friend telling you all of this. What would you tell her?
Be your own best friend.
Parting is hard, but don’t you really deserve someone who puts you first in their life? (…and yes you do deserve that.) Do you always want to be scrabbling after any crumb of consideration he chooses to throw your way? If he hasn’t responded in 3 years in the manner that you need, then why would he change if you just hang around?
This doesn’t mean he’s a bad person. It simply means that at this time & place he is unable to fulfill your needs. He may never be able to and wanting it badly won’t make him suddenly see the light. There’s no magic phrase or act that will make him wake up and be the person you need. (Notice I didn’t say “want”.) Staying in a situation like this is the equivalent of clubbing your self-esteem like a baby seal.
There is nothing wrong with wanting/needing someone to think you’re special. That desire/need doesn’t make you selfish or vain.
Fill your life with the things that make you happy. Get rid of the things and people that don’t contribute to your goal of having a happy, rewarding relationship with someone who thinks you’re special. You can’t find that person if that space in your life is taken up with someone who is apathetic about your wants and needs. It’s taken 3 years to learn what you need, what works and doesn’t work for you, so it’s not wasted time, but now it’s time to make yourself happy.
Life is too short.