@rea7 - I completely understand the distress you're feeling over this. It's a scary thing to feel like a prisoner of your own mind.
I'd just like to point out that what you're doing right now is known in OCD terms as "reassurance seeking." It's an extremely common compulsion, and it's a very sneaky one.
"I just want to know for once if this is all in my head or true, and then I’ll be fine."
^ This right here is absolute textbook OCD logic. I'm sure it legitimately feels like you'll be fine after you gain some reassurance, but I can promise you that it will NEVER be enough. I know that sounds pessimistic, but it's an important thing do understand. This very app includes the ability to flag posts as "seeking reassurance" for this very reason. It actually does more harm than good in the long run.
And I understand that it feels like these thoughts are unique to you. You'll just have to trust me when I say that I'm sure they aren't (or at least I'm sure they aren't any more horrible than many others). The reason I know this is that I've spoken to several OCD specialists and therapists in general, and they ALL say that everyone who comes in thinks that they have it the worst. Everyone thinks that their thoughts are too terrible to share. Everyone is embarrassed, and everyone wishes that they had a different "theme." I felt the same way when I was getting my own treatment.
I'm sorry that the person you told didn't understand. I promise you that if you speak to a professional OCD therapist, they will NOT judge you in any way. I know that's hard to believe!
As far as ERP exercises go, please keep in mind that I am not a professional and I don't know the full details of your story, so take anything I say with a grain of salt. With that out of the way, here's something general you can try.
Once a day, set aside a very short amount of time, maybe 5 minutes. For these 5 minutes, you're going to do your best to allow the thoughts to do whatever they want to do. You aren't trying to get rid of them, argue with them, or indulge in them. Simply acknowledge that they are there, nothing more nothing less. As the thoughts arise, you will start to feel anxious, and that's a good thing. You want to feel anxious, because during these 5 minutes your goal is to notice and learn how anxiety presents itself in your body.
Focus your attention, as best as you can, on your body. What does your chest feel like? How about your arms? Are you clenching your jaw? Does your belly feel tight? Is your breathing shallow or deep? Fast or slow? This is your chance to explore and learn with curiosity. Pretend that you are an alien that just inhabited a human body in an attempt to learn about our species. You want to learn what anxiety FEELS like. You don't have to get too analytical, but maybe give your anxiety a number from 0-10.
During this time, you're going to feel an incredible urge to get rid of the thoughts. You're going to want to disprove them. That's okay. Any time you feel that urge, just say, "I am aware of these thoughts, and I'm aware of anxiety," and return your attention to your body. Remember, you don't have to get rid of anything. You're learning.
Towards the end of the 5 minutes, see if there's anything you can change about your posture to bring yourself into a more relaxed physical state. Maybe you can let your shoulders drop a bit, unclench your jaw, or shift the way you're sitting. Maybe you can breath more slowly, allowing your exhales to last longer than your inhales. Don't try to force yourself to relax, just change a few things and notice what it does or doesn't do to your overall feeling of anxiety. Did your anxiety number go down, or up? Again, you are here to learn, not to get rid of anything.
After the 5 minutes are up, reward yourself. Have a snack, watch some entertaining videos, or whatever makes you happy.
If you do this properly, you may eventually start to understand that the anxiety you so desperately try to avoid feeling simply comes and goes on its own, without the need for any compulsive behavior. Emotions like anxiety WANT to be felt. We don't realize how much of our suffering comes from not wanting to feel certain things because we're afraid we can't handle it.
Ok I've written enough for now. ERP is a bit more involved than what I'm describing, but I hope this exercise can at least set you on the path to success.