When it comes to mental health disorders I'm afraid any sort of exercises designed to deal with the mind can be dangerous. When I was going through a period of very bad anxiety and OCD, meditation had the exact same effect that you described. Each time I'd sit, within 3 or 4 minutes I'd have a panic attack. I now meditate daily and it helps keep my mental health issues at bay.

However, what you did with your therapist was a guided meditation, not mindfulness meditation. You mention you're scared of what you'll find if you go looking - meditation isn't about going looking for anything, it isn't even about exploring things that might turn up - not until very advanced stages anyway. This is my main qualm about guided meditation sessions - they are often designed to evoke certain emotions and memories that you may not be ready to confront yet.

Try doing this. Sit down in a quiet place, close your eyes, then focus on your breath. That's all, just focus on the breath coming in and out of the tip of your nose. Count the breaths up and down to ten if it helps you focus. When you do notice a thought, whether it be "breakfast was nice today" or "the root cause of my anxiety is the time my Father did such and such to me as a child," simply acknowledge it (by which I mean notice that you're thinking about whatever it is you're thinking about instead of focusing on your breath), and then return to focusing on your breath. Don't entertain the thought. That's mindfulness meditation.

It sounds like you're in the exact place I was when I started with regards to your outlook on meditation - I also thought meditating was all about delving into the mind, and whenever I tried it I'd have a panic attack. Don't be scared. For now, meditation is simply the art of being able to concentrate on your own breathing, and noticing when you're not concentrating on your breathing. Practising meditation gives you the ability to notice when you're thinking unhelpful thoughts, and then do away with them. That's all it is really.