I need a little bit of that help only Reddit can provide.

So I just broke up with a girl last week and out of nowhere she starts blowing up on me and threatening me, after we have been broken up for a week. All she has threatened so far was to spread around some lies about me to the school and decided it would be smart to mention something about my dead brother being a joke excuse for me to be sad. So I decided I would be a bit more thorough with my revenge. Normally I wouldn't stoop to this level but mentioning my brother, who died in a motor cycle wreck when I was younger, was the final straw. So I'm asking for your help reddit. TL;DR- ExGirlfriend is spreading rumors about me and mentioned dead brother. Want some payback and I need Reddit's help.