I have created the following resources for OCD sufferers: https://www.ocdandanxietyresources.xyz/ Please have a look at it. It has links to plethora of information and support options.
You should get him an Ocd specific therapist! Try Noocd they're super good! :)
Good on you for reaching out to support your son. OCD is horrible and having people who care and support is really helpful. What does your sons OCD involve? By that I mean what are his obsessions and compulsions?
There's a guy called Mark de Jesus on YouTube who is very good with OCD since he has suffered with it. His videos on the 7 distortions are a good place to start. Usually OCD sufferers seek a lot of reassurance that they are not bad people, that they aren't crazy or losing their mind and that stuff like that. It's hard for a parent not to give reassurance to a son but you yourself will need to resist the urge to do so. You can say to him: "I love you and I'm here for you but it is you that needs to realize that it's just a thought and you are not your thoughts but only the observer of them". Just be there for him but be aware that you aren't being pulled with his obsessions and you end up constantly reassuring him. Take care of yourself. Realize it's not your fault not his. And like you are doing get help and be familiar with the topic. It's hard but with time, patience and intentionality it gets better but it's him that will need to do the heavy lifting you are just there to support him. Compassion is the key and him learning self compassion it's crucial. Hope this helps.