Girlfriend Problems! Need help!?

Me and my girlfriend have been dating for over 4 years.I used to love her,but im not "There" anymore and I do not think she is either.We have not been apart for more than 1 day in over 4 years. She is bossy,she tries to control my everymove.When she is at work and she calls me during the day,she is the nicest person on earth,but when she gets home she is a total "B".Its like night and day! Tonite I let the dogs out,we have 3 dogs,they went to barking,and the neighbors,which we have many,told us to shut them f-ing dogs up.I was mad at this and wanted to let the dogs back out to bark again to see who told us this,being the "Man" I am..lol. When I went to let the dogs out she hit me with a "Frying pan" in which busted my arm and sent me to my knees.I do not understand her and why this happen,I pay all the bills,always have,she gets everything she wants when she wants from me.What would make someone who I am in a relationship with,Hit my Azz with a frying pan for standing up.Let me know!