I think not accepting your stutter is what is "ruining" your daily life rather than the stutter itself. I know it might be hard to accept this part of you but that's just your way of expressing yourself. Don't stress so much about what other think about you and speak freely, your way. If you girlfriend decided to broke with you because you stutter, then it is better that way, I wouldn't like to be in a relationship with someone who doesn't accept me for who I am.