OCD International has excellent resources, including listings of therapists that specialize in OCD (very important). This is where I found my daughter’s wonderful psychologist.
Shala Nicely, LPC is a therapist specializing in OCD. She has been kind, classy, and giving in my search to find help for my daughter. Her website has excellent resources. She is the author of several books on the subject. Is Fred in the Refrigerator? and Everyday Mindfulness for OCD. Both excellent!
Jon Herschfield, MFT has written many great books on OCD–and Harm OCD specifically. Overcoming Harm OCD is one of my favorites. I’d recommend any of his books. He also has many helpful talks that can be found on YouTube.
OCD can often lead to attempts to self medicate with drugs and or alcohol, compounding one serious problem with another. If this is a situation you find yourself in, you need a treatment center that is able to address both issues at once. https://www.therecoveryvillage.com/mental-health/ocd/