Hello @stefani!
Wow, what an experience! Sorry to hear it left you feeling uneasy and anxious. Haley and Francisco offered some very plausible causes for what happened- I absolutely agree about purifying and cleansing the outside of your house (and inside, especially your bedroom and around your bed). You might want to try an Energy Cleanse or Protecting Your Home with Salt.
Since your pendulum gave you a strong indication this relates to Hekate, I would suggest trying a ritual or spell to reach out to her. A meditation in Her name may also help to give you more answers. If indeed this is related to a past criminal case where justice was never given, I highly recommend this Hekate Devotional Prayer for Justice:
I hope that peace returns to you and your household soon! And sending good thoughts to your sick kitty- I wish him a very speedy recovery 
Good luck and blessed be!