I'm sorry you went through this. Please consider going to therapy about this because it sounds very distressing and it's difficult to deal with something like this on your own. <3

With that said:

**I am not a therapist**

I have OCD. With thoughts like this, what my therapist tells me is that it's important to sit with them and just let yourself experience whatever you are feeling. OCD is a cycle: you have a thought, the thought produces anxiety, you act on the thought (e.g. through a compulsion) because it makes you feel better temporarily... but actually, acting on the thought makes the anxiety worse because it tells your brain that you had something to be anxious about. So unfortunately, by doing the things that make you feel better (like showering), you can end up making yourself feel dirtier.