Dear Bob,
Even though it may not feel like it, you are at a great place right now! You see, you have the opportunity to make permanent changes that will positively affect your relationship and life. If your girlfriend broke up with you for "criticizing her and arguing with her" there are reasons these behaviors occur.  The first step is to begin with looking within yourself.  Often times, these types of behaviors are the result of unresolved anger, pain, and resentments.  Commonly these types of feelings initiate in childhood. Your job is to figure out where these feelings are coming from and then take the steps to resolve and heal them.  Until the core issue is discovered and healed, you will continue to ultimately exhibit these behaviors with your girlfriend or in any future relationships you may have with other woman.  If you choose to do this for yourself, I would communicate with your girlfriend your decision to heal and ask is she can be patient while you work through this.  If she still loves you and wants the relationship, it is likely that she will be hopeful by your choice and want to work on the relationship.