Fiancee believes our relationship is toxic & that i have anger issues! Advice?

Im 30 and have been with my fiancee 2yrs, engaged 6months, She is 24. I love living with her and waking up beside her everyday. I travel alot with work & can be gone for up to a month without her although she comes with me whenever possible. Although i loved her so much, I am easily pissed off and have a temper on me, if we where having a disagreement i shout at her, smash something against the wall or sometimes even punch the wall/door & if she'd try walk away from me i'd grab her arm & i know i shouldn't, the she'd throw something at me when i walk away, Other times i'd speed in the car when she'd beg me to stop, But when we are not fighting we couldn't be happier, I always tell her how much im in love with her and want to marry her, We always have our hands on each other, snuggle and our life is unbelievable. I grew up in a home where violence was the answer to everything, but i would never hurt her intentionally but she knows how to push my ons and i'd always lose the head with her and it would kills me seeing her cry, we always make up and she'd call me a f*cking a*shole among others that we laugh about later. Our friends say we have a toxic relationship and don't know how we lasted together. Its like we love each other so much & yet hate each other so much that we cant stand to look at the other. The thought that she'll eventually want a better life kills me to think about, She is the love of my life & im willing to work on my faults i just cant imagine being without her for the rest of my life, Any advice?