Thanks for sharing this story. I found this article on the pentagram that I thought was helpful. http://www.patheos.com/blogs/badcatholic/2012/09/5-things-people-think-make-them-hardcore-and-why-they-actually-make-them-christian.html#disqus_thread

A good prayer against evil is the St. Michael prayer,

Saint Michael the Archangel,
defend us in battle.
Be our protection against the wickedness and snares of the devil.
May God rebuke him, we humbly pray;
and do Thou, O Prince of the Heavenly Host,
by the Divine Power of God,
cast into hell Satan and all the evil spirits
who roam throughout the world seeking the ruin of souls.