it is possible to re-build a personality, i know,,, it's not easy, usually, not quick, but it lasts a lifetime, it's a good investment of time and energy. here is the recipe i learned for change:

Decide: decide you are going to change, decide what you are going to change, decide to change as much as you can whenever you can.

Notice: notice when you are using the unwanted behavior. notice the effects it has on you and others. notice what thoughts or feelings came up just before the unwanted action.

Change: change to the desired behavior as much and as often as you can. make the effort, let nothing stand in your way. it's work, make the effort.

Praise Yourself: whenever you manage to change even a little, or when you notice something you had not been aware of before, or when you reinforce your commitment to try harder next time,,, give yourself a pat on the back, a kind work, some praise. the inner child craves approval, give it freely.

i hope you find success and new beginnings~