Ugh. Yes, simplistic, overly rigid stuff like this is a good example of why CBT drives me up the wall too. So many therapists use it like a bludgeon to just insist that you should stop believing something--which can feel like gaslighting, or manipulation, or just plain disrespect, depending on how it's handled and what your personal history is. It seems like it might be more productive to explore what seeing yourself as a "loser" means to you, what your feelings are around the reunion, etc., in more detail, rather than rushing in to label with terms like "cognitive distortion" that aren't useful for you.

If you feel allergic to CBT and don't want her using it, the therapist should respect that--end of story. It's very odd to me that she's insisting on it even though you've made yourself clear.