You're the boss. If you were the lead mare would you let a horse kick you? No, you'd turn around and beat the other horse's butt.
I'd carry a crop and if she kicks, I'd whack her on the butt with it.
Sure some people might think it's 'mean', but I'd rather the horse glares at me, then my having to be rushed to the hospital cause my horse shattered my leg.
I'd also look in to possibly having a training/experienced horse person come in every week or two, to make sure you aren't letting your mare develope bad habbits. Just a thought... :)