Yes, talking about it with her would be fine, unless she tells you otherwise, but you are right - if you have a pattern and obsessive thoughts, talking about it is part of your therapy. It is also true that it you acknowledge out loud to someone that you feel like doing something, you are much less likely to do it than if you keep those thoughts secret. Your T may actually be more comfortable with having you talk about what you are thinking than with not knowing where you are with those thoughts.