This is always a scary thing to bring and spoken about it with two Ts, my current one and a previous one. I just came straight out with it and neither of them seemed uncomfortable about. In fact, the first T said she has had a number of clients experience this issue and only one of them was unable to get past it. My current T has a bit of a different approach and asked me a lot of questions about it to try and find the deeper meaning behind it. She didn't seem surprised or shocked about anything I talked to her about.

I think you should just come straight and say it. You will anxious at first but hopefully once you have spoken about you will be glad you did and be proud of yourself. I'm sure your T would be proud of you too