Fight crazy with crazy? Invite her to your basement and be sure to dig a lot of holes in your yard and leave out a lot of garbage bags and saws. Buy some cheap wigs and put them in buckets filled with toilet bowl cleaner to give off acidic fumes.
You guys doing this all wrong, when a psycho wants you bad just tell her you would love to be with her if only this other girl(one you can't stand or is even more psycho) is out of the picture, then you just sit back and watch.
I know they didn't license the Juventuz brand. But as a shout out to @GordoDeCentral, that just makes me feel like a footie club got bought by this guy:
You guys doing this all wrong, when a psycho wants you bad just tell her you would love to be with her if only this other girl(one you can't stand or is even more psycho) is out of the picture, then you just sit back and watch.