i think that you must chase the good in your life.
this situation (want sth back) cause you stress and can’t give you stability.
this can only upset you,can’t you see?
and it can effect your health.
try to realise that,and ask yourelf if every action you make cause you happiness or unhappiness.
i think that when you will truly fell happy with yourself and your life 100% you will not wanting ANY ex or any difficult situation like this.
because wanting something or someone back,means that you have regrets or unhappy feelings in your life.
i know it’s sometimes difficult to let go, i must say that i lived this way in a time,and maybe sometimes these feelings make me unhappy,but it’s in your hand to get over all these and try to find sth good in your life.