Thank you for this question. This is a difficult and painful topic to discuss, but it is an extremely common sentiment that people have after experiencing assault or abuse. If you experienced assault or abuse and are feeling this way, you are not alone. Many survivors struggle with these feelings of being "dirty" or disgusted with themselves, and there are several reasons why this happens.
Trauma can deeply affect how we perceive ourselves and our bodies. When our personal boundaries are violated, it can lead to a sense of contamination or a feeling that our body is no longer fully our own. This isn't true, but it's a normal reaction to an abnormal and traumatic situation.
Society also often perpetuates harmful myths and stigmas about assault and abuse, which survivors might internalize without even realizing it. This can lead to unwarranted feelings of shame or guilt, even though the abuse was absolutely not your fault.
Sometimes, the intense negative emotions associated with the traumatic event become psychologically linked to our self-image. This can result in feelings of self-directed disgust or revulsion. It's a psychological defense mechanism, but it doesn't reflect reality.
Many survivors also experience a form of cognitive dissonance. They struggle to reconcile who they were before the assault with their experiences and emotions afterwards. This internal conflict can manifest as feelings of being "dirty" or feeling tainted afterwards.
It's crucial to understand that while these feelings are common, if you are experiencing these things, they are not a reflection of who you are. You are not dirty or disgusting - you are a person who has experienced trauma. Your worth and value have not changed.
Healing from these feelings is possible. Many survivors find that working with a therapist or sharing these feelings with other survivors who understand can be incredibly helpful in processing these complex emotions. Support groups can  provide a space to connect with others who understand what you're going through or even just trusting to other trusted people in your network who love and care for you.
Remember, you're not alone in experiencing these feelings, and they don't define you. You're strong for surviving and for seeking to understand these emotions. Be patient and gentle with yourself as you navigate this healing process. You deserve so much more than what you have experienced. Thank you for asking this. You are not alone.