Breaking up with fiancé

I broke it off with my fiancé of 5 years and father of our 2 daughters because he just made me unhappy, treated me like crap & done me wrong . He never went as far as sleeping with another girl (not that I know of) but the texting, flirting, dancing etc etc. now that I’ve finally decided to leave him and put myself first. I just cannot understand how he has the audacity to tell me “and you think breaking up is the best option”, “stay and watch me change”, “you just want what you want” blah blah blah. How can this dickhead not understand that im leaving because he’s a shit partner, untrustworthy, unfaithful & hypocritical & I just cant continue being unhappy and think that’s I’m doing this because I just want to. Its the last thing I want to do!!!!