You cannot undue the choices you made in the past but you CAN now make other choices in the present.  You did then what you felt was the right choice for you but have since discovered that it is not. You have learned from your own experience and that is a great thing!  So what do you do? Make a different choice now.  You can always choose to make different choices because you have the agency (ability) to do so.  To have no regrets  is to have lived a life of stagnancy. Namaste.