Aggressive dominant mare?

So I brought home my 3 year old gelding today, I have another 10 year old Canadian gelding . And a 14 year d arabian mare,she is a very nice mare, but I have spoiled her too much so now that there is this new boy she is kicking at him and snapping at him threw the fence, I have neve seen her so miserable. She ran by And kicked at me and lunged at my friend when she was petting the older gelding . She was all happy when I was grooming her and it's not like I'm not giving her attention, she is still getting most of my Attention, and it was never a problem before she has never been aggressive, I actually don't know what to do and I am NOT getting rid of her, the geldings are great together , it's just the mare. She has great ground manners and is very respectful, just I dont know what's wrong with her..