Sorry to hear you're going through this! Believe me, I understand where you're coming from, and I'm all too familiar with suicidal/existential intrusive thoughts. So hopefully it helps to know you aren't alone.
Are you seeing a therapist that practices ERP? If not, it's definitely worth considering, as it's currently the gold-standard for treating OCD.
It's also very helpful to become familiar with what exactly OCD is, and what's really going on here. A quick summary:
Intrusive thoughts come in all shapes an sizes, and are experienced by everyone from time-to-time. The content of the thoughts don't matter. What makes them intrusive is that they are thoughts that you don't like, and cause you to feel anxiety.
In reality, these thoughts are harmless, and will simply come and go. Problems begin to arise when we try to ACTIVELY get rid of these thoughts and/or the anxious feelings associated with them. The actions that we take to try to get rid of the thoughts/anxiety are called compulsions. Compulsions can be physical (excessive hand washing, step-counting, skin-picking, etc.) or mental (reviewing, ruminating, researching, etc.). Mental compulsions are particularly hard to detect.
So why are compulsions a problem? The issue is, by taking an action to get rid of a thought, you are training the brain to label that thought as something that is dangerous and really important. While compulsions may bring temporary relief, the thoughts will return, and they will return more often and bring with them more anxiety (because, again, you've trained the brain to think that they are super important).
Whether or not someone has OCD depends on how long and how often they are caught in this obsession-compulsion cycle. Someone without the disorder may experience this cycle from time-to-time, but it generally doesn't take up much of their time. People with OCD, on the other hand, can spend hours-upon-hours caught up in this cycle, severely interfering with their daily life.
The single most important thing to understand here is that neither the thoughts themselves, nor the anxiety, are the problem. The COMPULSIONS are the problem. You have no control over what thoughts randomly arise, or the spike in anxiety that comes from them, but you do have control over the compulsions. That's your key to breaking the vicious cycle. If you can limit the compulsions, the thoughts will occur less often, and the anxiety will be less intense.
The ultimate goal of ERP (exposure response prevention) is to learn to sit with and really feel the anxiety. As you practice it, you will notice the anxiety come and go on its own, without you needing to "do" anything. It is deeply rooted in mindfulness.
Eventually, you might have a thought like, "what if nothing is real, and this is all a dream?", and while it may make you feel a little uncomfortable, you'll be able to respond (not react!) with something like, "that would be strange, wouldn't it?", and be on your merry way.
I know right now that literally seems impossible, but you have to remember that we are dealing with highly illogical parts of the brain here. I can't stress it enough: it seems like the intrusive thoughts are the issue, but they aren't. We're dealing with FEELINGS here.
I hope something here is helpful. Happy to help with any other advice :)
