Hi Emma, I'm glad you have a Therapist. What I would say to you is I am learning to deal with intrusive thoughts and worry thoughts by basically employing mindfulness techniques and labelling a thought as just a thought.
As a previous poster put, they are not actions and just because you think about something doesn't mean you are going to do it.
A thought is an electrical message from one brain cell/structure to another, not necessarily FACT.
I am practising just observing thoughts, take a step back, just notice and neither cling to or push away the thoughts. Let them flow in and out. Think of your mind as if it was a non stick pan. What you cling to gets stronger as you add other judgements to it such as 'I shouldn't be thinking this thought' why not? It's just a thought. What you try to push away keeps returning faster and stronger as you don't have the mental energy or ability to 'ban' thoughts at the door. If I said to you right now, don't you dare think of an orange banana, what comes to mind? Most likely an orange banana so don't 'ban' thoughts just notice them, and get on with whatever you are doing. It takes practise but eventually you start to gather the evidence that you haven't turned into a murderer etc and the thoughts are having less of an emotional impact on you.