Hello and thank you for posting.
I'm afraid I'm very unclear as to what you're accusing yourself of? Do you mean of being HIV positive, or of passing it on to someone else?
Whatever it is you imagined, it is important just to move on from it. You're a sane person; you didn't do whatever it was. If it's a past thought, then it's a thought, only that.
If it helps, I used to doubt whether my thoughts were memories and vice versa. It's just not healthy to keep going over them, as memory is not an accurate recording device. It's the past as we see it, not a recording. Forbid yourself from thinking about it as much as you can. Remember what you have done to prevent/compensate for it, and then think forward again. It's in your past. It doesn't have to be your current, or your future.
Make a point of deliberately thinking other things. Anything from what your plans are for the rest of the day, to a piece of music, to a TV storyline. Anything. Just put your mind onto something else, every time this past thought rears its head. Eventually you'll be able to train yourself into not thinking about it at all.
It's not a quick fix, but it's better than nothing. And as is often the way with these things, the best way is often slow and steady.
You say you're seeing a therapist and this is a good move forward. But remember, you have an active part to play in that. Just a therapist talking to you doesn't mean they'll take the problem away for you. You have to work with him/her. Are you doing so?
