How long does it take to move on


I have been hang up on my ex for almost three years now and we only dated for a year. We were very sure about each other and planned our future. I dated other people before and also after him but no one fits my world like him and he did love me deeply. We broke up because of a mistake I have made but he refused to forgive me and made the final call to break up. Yeas after, recently, we accidentally met and he told me he is in unhappy relationship and that regrets that he didn’t forgive me but he is in another relationship and he wants to stay loyal since she hasn’t wronged him in anyway and it won’t be fair to leave her.

How long does it really take for a person to move on?

Is being stuck for three years even healthy?

How do I move on? Specially when I feel that he still have feelings for me?