Pure O thoughts are made up in our own mind. It is like me looking at someone and thinking something bad about them and then saying to myself "No I didn't mean that." I think an OCD mind goes to the dark side a lot. We come up with thought that are truly horrifying to us. I mean why would we waste our time on things that are mundane right! We need to take ourselves down the dark path. The good news is that just because you think it doesn't make it so.
I once thought I would harm my husband. My therapy was to sit in a dark room and actually picture myself harming my husband. What you quickly learn is that the person you are imaging is not you and that you wouldn't do those things. We are not doers...we are thinkers.
It is a hard cycle to break though without the proper tools so I do suggest you seek out the help of a psychologist who can teach you cognitive behavioral therapy. Your life will be so much better for it.
I know how you feel and you are not alone. I'm sure you hear that a lot and it may feel lonely anyway. But you really are not alone. The mind absorbs everything like a sponge...pleasant and unpleasant. Try not to judge the thought. It helps to not give it power.
There is an app that was recommended, it is called headspace. Helps you think about thoughts in a different way. I wish I could say the thoughts will go away or that you will be cured but that is not certain.
In my experience, the thoughts are there 24 hours a day and it used to send me in a constant depressed state. I had to be hospitalized because of suicidal ideation and found out about OCD pure o. Did some research and I feel a bit better. The thoughts are still there but that's all they are to me now...just thoughts. It is a little sad to accept this but it is better in the long run to keep yourself healthy and happy. Hope today your thoughts are more peaceful. Be well. :)